Why give it the same name as a fake ship though?  And copy the bridge décor of a ship that's not even a Federation design but put on some fake Starfleet LCARS for a day??
I get the need to make a Voyager reference, but I feel they'd have done better to use the Vesta-class quantum slipstream ship from the novelverse instead.  It's a reference too far, since the closer you look, the less it works.
		
		
	 
Voyager crew got DETAILED sensor scans of the ship from the inside out. They basically got to learn how to use the ship through a fake interface no less (which DID work btw because the fake LCARS interface was like a translation skin for the underlying alien UI).
I guess that Starfleet simply had a look at the design and said: 'this is doable, but certain things need to be changed externally to make it a reality.'
After all, prior to VOY encountering Slipstream technology, Starfleet hadn't even hypothesized or theorized about it. and VOY only made the v1 of the technology work with Quantum Stresses... and with V2, the quantum stresses were no longer the issue, but calculating proper phase corrections was.
Its likely that Arturis Dauntless had a more Slipstream decidaced computer technology capable of doing that... and knowing Starfleet, they'd probably just want to TEST the thing properly before they decide refitting their entire fleet with the thing (after all, we don't want a repeat of what happened to VOY in 'Timeless').
So, from Starfleet's point of view, I guess they thought: 'if the original design works well with Slipstream without issues VOY encountered, then we can certainly do it ourselves but our technology IS a bit different and the ship's hull will be slightly different as a result, BUT it WILL work regardless.'
Say what you will, but the Aventine isn't canon (at least until/if they decide to make it canon)... and as I mentioned before, the writers could still introduce the Aventine as a second Slipstream dedicated ship if you will.
As for why they'd name it 'Dauntless'... well, its possible that Starfleet wanted to pay a tribute/homage to Arturis species for them being (completely?) assimilated by the Borg (which WAS in part VOY's doing because Janeway did help the Borg to fight species 8472 at the time - granted as Janeway pointed out, 8472 said back then they intended on destroying everything, so might as well go with the Borg - or an enemy you DO know and is native to the galaxy - plus, 8472 wasn't giving us an impression they were willing to team up with VOY... nope, they wanted to PURGE the galaxy).
EDIT: as others noted, Starfleet probably didn't feel the need they had to change the bridge design or internal layout much/at all because it was already mostly similar to Starfleet's... plus the original design seemed to have been Slipstream only... no Warp drive (unlike Starfleet's version). Best to keep changes to a minimum.