This is "normal" if you installed Ubuntu with UEFI with Secure Boot enabled.
one is the normal boot loader, Ubuntu (XXXXX) and the other is the signed one, ubuntu (XXXXX), you can see the diference one begin in Uppercase, the other one in lowercase.
for UEFI with secure boot enabled go with ubuntu (XXXXX), the other one never launch because is not signed. you can delete this one with
efibootmgr but is no problem if you leave this installed.
you can check your boot entries in your system with:
sudo efibootmgr -v
and after this, check
man efibootmgr, and if you like, delete the boot entry that you are not going to use, the signed one or the normal one.