How to duel boot Centos 7.9 Rocky linux 9.3 from same hard disk

[Mahammadasif]

I am trying to duel boot Centos 7.9 Rocky Linux 9.3. First I have installed Rocky Linux 9.3 in separate partition it worked properly I can see the grub menu for Rocky while booting. For the duel boot I have installed centos7.9 on another portion and restarted the system but now I can able to see only Centos grub entry, Rocky Linux grub entry disappeared from menu. I have tried to add custom entry in centos for updating list I tried grub2-mkconfig -o /boot/grub2/grub.cfg but it is not working. Centos grub version is 2.2 and Rocky Linux Grub version is 2.6. Please help me on this