Your question is still somewhat ambiguous and unclear to me (Blaming myself). I'm answering this considering each case:
Case 1: Mount iso which is within another iso file
If you are asking whether you can mount an iso file which is within another iso file, I would say, Yes, You can mount an iso file which is itself in another iso file
For example, Let us assume we have an iso file named
file1.iso in our home directory and there is another iso file inside it named
inside.iso. One way to mount both iso file is ---
Create two folder in your home. Each for each iso file.
mkdir ~/iso1 ~/isoInside
Mount the first iso file in the ~/iso1 directory
sudo mount ~/file1.iso ~/iso1 -o loop
Then mount the second iso file inside this iso to "~/isoInside" directory
sudo mount ~/iso1/inside.iso ~/isoInside -o loop
Now you have the first iso file mounted in "~/iso1" folder and the second one in "~/isoInside" folder
Case 2: Mount two iso file in a single directory.
If you are asking whether you can mount an iso file to a folder and then mount another iso file in the same previous folder, I would, Yes, you can do that also. But You cannot access the content of first mounted iso file.
That is, if you mount an iso file
iso1.iso in a folder, say
/mnt and then mount another iso file
iso2.iso in the same folder
/mnt, you will only see and access the content of
iso2.iso file in
/mnt. You cannot access the contents of
iso1.iso file in
/mnt folder until you unmount the second iso file, i.e
Take note that, in such cases, you cannot either unmount the first iso file. You must unmount the second one and then first one.
I think, you are having a problem with installation from an iso file (probably from alternate installer iso), if this is indeed the case, I suggest you to ask a question about your problem.
Hope this answer will help.