Yes, many mosses change their habit considerably depending on growth conditions - lighting, nutrient and CO2 supply, emersed/submerged etc. It may well be that submerged grown pieces of mosses which normally grow terrestrial are not determinable for the experts (bryologists), because the microscopical features, crucial for ID, are changed, resp. the submerged habit isn't described in scientific literature.
For IDing moss from outdoors, it's best to send a sample collected in the place where it grows wild, not yet grown submerged in the tank.
As for mix-up, even moss growing outdoors may be a mix of different but similarly looking species.
"Java moss": may be considered trivial, but actually interesting. The common "Java moss" widespread in the aquarium hobby, mostly called Vesicularia dubyana, was IDed as Taxiphyllum barbieri. But T. barbieri is known to the science as native to Vietnam, not other countries. So every aquatic moss from outdoors, considered to be "Java moss", is noteworthy.
(True V. dubyana that's now called "Singapore moss" in the hobby is widespread in tropical Asia, according to literature. The original "Java moss", cultivated in Europe first, many decades ago, was indeed V. dubyana, likely from Java)