@SonoMichele the first issue was that osprober created wrong grub entries . I had to manually add the grub records so that I could boot into my second linux
After all this when I mounted my first arch install to copy over file . Idk for some reason it was not able to boot into the first one after powering off. I had to go into live USB format the boot partion and regenerate the fstab and force install the linux package to generate the boot images (this took me an entire day to figure)
@SonoMichele No , give it a shot .I learnt a lot from doing this