why do i have 2 phones in my icloud backup?

What do you need help with? If you upgraded from a previous iPhone, one of the backups may be from your old phone. Or, if you have tow phones sharing the same iCloud account the second backup is probably from the other phone.

If you don't need the backup of your old phone you can safely delete it from your account to free up the storage. To do this, just tap the backup, then tap Delete Backup.