GMail Address Variations
In GMail Help to a question about “Am I receiving someone else’s email?“, it explains how GMail assigns and handles a username. One username is allowed per one registration. Once it is assigned, Google prevents the insertion of dot(s) in this username. Whether emails sent to email@example.com or to firstname.lastname@example.org are all yours. However, when you log into your GMail account, you need to type the original version you registered as username.