better pics for sure are needed for a positive ID. On why two seemingly different looking pleco's can both be common, there are several different sub types of common pleco and not all of them look exactly the same. Also each one will vary slightly in its patterning.
However, to my eyes the small one looks like it has spots instead of the typical common pattering, that would definitely make it a different L number. But based on the blurring in the picture that could simply be the standard patterned blurred.
long story short, take better pictures!