The TNG-era starship(s) USS Lexington are referenced a handful of times.
1. mid-2365: "The Measure of a Man" TNG2 SB173-SDS chart, registry NCC-30405
2. mid-2370: verbal reference to rendezvous with Enterprise 1701-D in "Thine Own Self"[TNG7]
3. late-2371: docked at DS9 ("Explorers"[DSN3]), Nebula Class, registry not visible (re-use of USS Prometheus)
4. late-2373: verbal reference, casualty report from Battle of Sector 001 (ST:FC)
The Starbase 173 display from "Measure of a Man"[TNG2] suggested a Lexington 30405 in mid-2365. Then "Explorers"[DSN3] showed a Nebula Class Lexington in late 2371 that was considered a plum assignment a couple of years prior (2369), as might be the case for a newer ship, and a newer ship was shown. (It was scripted to be a Galaxy Class ship but ended up as a re-use of the shot of the Nebula Class USS Prometheus, NCC-71201.)
As of that moment, there was no contradiction. Lexington 30405 existed in mid-2365 and a new Lexington existed in 2369.
So, the worst thing that could happen at this point is if someone like Okuda tried to give the new Lexington a weirdly low registry. And indeed, Okuda decided to give the ship the registry of NCC-61832 for the Encyclopedia.
Well, dammit.
Chronological registries are a thing, and 61832, being around 10,000 less than the Galaxy Class ships like the Lexington ought to have been, is way too low for a new vessel. That would likely be a ship of the early 2350s.
Okuda's Nebula-Lexington registry, if accepted, is so old that it must overwrite 30405, as it would be a vessel at least several years old as of 2365. That also seems at least a little contrary to the ship being a plum assignment, though that part's not insurmountable.
The alternative is to reject Okuda's backstage Nebula-Lexington registry as an unnecessary contradiction or overwrite. There are two ways to do this. One is to just go with 30405 and slap it on a Nebula. That's stupid and no one would ever do that. Another alternative is to presume that there's a higher Nebula-Lexington registry.
There's support for the latter. A little bit of brightness on one of the docked ship shots makes it obvious that the Lexington's lower saucer registry is something that starts with a 7.
Of course, we know it says 71201 due to Prometheus 71201 shots from the other episode, but this shot is sketchy enough to leave wiggle room ... 71XX1 is easy enough to argue for, but one must be cautious here because 71XX1 could cause its own problems. 71807 is the Yamato, and while she was only ever seen in 2365 there was evidence of her being in space for about the same amount of time as the Enterprise-D, observed throughout 2364. It's very tight to squeeze in any 71XXX registry toward the tail of 2365, and very dependent on exact sequencing.
(I'm currently working on registry progression analysis and there's at least one of the multiple current versions where, for example, 719X1 isn't impossible to fit in 2365 . . . one version features 2365 as 71842-72210, which even leaves 71891, for instance. However, more than one version doesn't allow that, so mileage may vary by the time I'm done.)
1. mid-2365: "The Measure of a Man" TNG2 SB173-SDS chart, registry NCC-30405
2. mid-2370: verbal reference to rendezvous with Enterprise 1701-D in "Thine Own Self"[TNG7]
3. late-2371: docked at DS9 ("Explorers"[DSN3]), Nebula Class, registry not visible (re-use of USS Prometheus)
4. late-2373: verbal reference, casualty report from Battle of Sector 001 (ST:FC)
The Starbase 173 display from "Measure of a Man"[TNG2] suggested a Lexington 30405 in mid-2365. Then "Explorers"[DSN3] showed a Nebula Class Lexington in late 2371 that was considered a plum assignment a couple of years prior (2369), as might be the case for a newer ship, and a newer ship was shown. (It was scripted to be a Galaxy Class ship but ended up as a re-use of the shot of the Nebula Class USS Prometheus, NCC-71201.)
As of that moment, there was no contradiction. Lexington 30405 existed in mid-2365 and a new Lexington existed in 2369.
So, the worst thing that could happen at this point is if someone like Okuda tried to give the new Lexington a weirdly low registry. And indeed, Okuda decided to give the ship the registry of NCC-61832 for the Encyclopedia.
Well, dammit.
Chronological registries are a thing, and 61832, being around 10,000 less than the Galaxy Class ships like the Lexington ought to have been, is way too low for a new vessel. That would likely be a ship of the early 2350s.
Okuda's Nebula-Lexington registry, if accepted, is so old that it must overwrite 30405, as it would be a vessel at least several years old as of 2365. That also seems at least a little contrary to the ship being a plum assignment, though that part's not insurmountable.
The alternative is to reject Okuda's backstage Nebula-Lexington registry as an unnecessary contradiction or overwrite. There are two ways to do this. One is to just go with 30405 and slap it on a Nebula. That's stupid and no one would ever do that. Another alternative is to presume that there's a higher Nebula-Lexington registry.
There's support for the latter. A little bit of brightness on one of the docked ship shots makes it obvious that the Lexington's lower saucer registry is something that starts with a 7.
Of course, we know it says 71201 due to Prometheus 71201 shots from the other episode, but this shot is sketchy enough to leave wiggle room ... 71XX1 is easy enough to argue for, but one must be cautious here because 71XX1 could cause its own problems. 71807 is the Yamato, and while she was only ever seen in 2365 there was evidence of her being in space for about the same amount of time as the Enterprise-D, observed throughout 2364. It's very tight to squeeze in any 71XXX registry toward the tail of 2365, and very dependent on exact sequencing.
(I'm currently working on registry progression analysis and there's at least one of the multiple current versions where, for example, 719X1 isn't impossible to fit in 2365 . . . one version features 2365 as 71842-72210, which even leaves 71891, for instance. However, more than one version doesn't allow that, so mileage may vary by the time I'm done.)
