I might have the cast of the original movie, meet the cast of the series--an alternate universe type deal, with the explanation that one team's meambers had the same names, but not the same genetic code. Someone was trying to fix a timeline. If one party found the other dead, it might make for an awkward moment.
I always had this fantasy of a Jurrasic Park for actors. Vincent Price's clone would only be allowed to be adopted by persons in a certain place, and the clone reared well away from distractions.
So you have nice dead ringers adopted by movie fans, but it all becomes rather dark at the last.
That might work between the two casts of the Stargate film and series in some manner--were I to helm the picture...