I'm watching Star Trek: Deep Space Nine right now

I'm almost convinced that they drew heavy inspiration from the changelings villains from that awesome tv show.

Thoughts?

Eh, I'm not convinced. While DS9 started in 1993, and BG1 came out in 1998, doppelgängers have been around at least since Ad&d, with the monster manual being released in 1977. "Dopplegangers replace important people" as a plot is even older than that.

Yeah, a changeling is nothing new, being common in folklore even in medieval times. Besides, changelings in DS9 are completely different than D&D: beings separated from a liquid-state communal whole. Nothing like doppelgangers.