white saum isn't the true GT. there are gold saums, white saums and then the true GT which also has white trimmed fins. there is a difference between a true GT and white saum. if you found it in your lfs for under $30 then it's a white saum.
when young blue acaras and gt's can be very hard to identify as they look similar but as they grow the difference becomes a bit more obivous.
I had a green terror that was sold as a blue acara and he was a mean little fish but attractive all the same.
i would be willing to bet you have a pair of green terrors. one male one female. if theres orange on the tail; probably gt IMO, my female is waaay darker and smaller than my male, but as she gets bigger, her colour is starting to come out. i bought them at the same time, the male is like 5 inches and the female is 3 or so. and shes just starting to colour. my male was very colourful right from the start.