It happens on rare occasions, Ghost shrimp can be confused with other types of the macrobrachium family,
This is a ghost shrimp
This is one of the species its confused for, the macrobracium acanthurus, as you can see, it's similar but identical, most species that it is confused for are bigger and have bigger claws because they are carnivorous.
However, it's rare cases and you can always double check if they look like in the picture, if you really want to be safe get amano shrimp, they are scavangers as well, omnivorous and algae eaters if you have algae issues.
Amano shrimp are the same size as ghost shrimp more or less, and almost transparent and opaque looking, you can tell they are amano shrimp by the lines across their body and spots :)