Blocked not spam users

Hello,
i have a personalized register form (you could see into page link). It doesn't show username field because it fill it with same value of email field. 

I explain this because some user wanted to register using this form and STOP SPAMMER blocked her. When i see her report into "Allow List Requests", i can se the reason is:

Username Too Long: 1,2,17,18,19,3,4,20,21,22,5,23,151,8,10,11,175,176,12,431,479,455,549,550,806...

I don't know where does this numbers come from and i don't find this when i revise my code where i fill hidden username field with email field value.

Some explanation. This situation have blocked some not spam user to register into my website but not all of them.

Some explanation?

Thank you.

The page I need help with: [log in to see the link]