Someone that did an order via Guest account, please chime in with missing gaps in following.
Can see situation where OP lost the reservation. Per following, OP was going to use girlfriend's Sprint account to order a phone.
https://forums.macrumors.com/threads/quick-question-carrier-info.2080788/
Guessing Guest account purchase still asks for cellco account information? If so, cellco account has Jane Doe name, zip, SSN. Cellco has an email on file? Buyer has different billing & ship-to name, address, zip, email. In a post Equifax era, and in attempting to curb scalping, can see where this order got red flagged.
And in same vain, post above linking different cancelled order thread: not entirely clear what that OP's situation is, but appears has different variations of name (including, appears, maiden-hyphen-married type name) that just don't line up. Throw in different emails, can see, again, extra precaution by Apple.