Disk Utility: Creates wrong CD/DVD master image from CD

Question

Level 1

25 points

Disk Utility: Creates wrong CD/DVD master image from CD

This is a very weird error. I am trying to make a CD/DVD master (.cdr or iso) image file from a CD using disk utility. I have 2 CDs with the same name. 6 files, one file is different between the 2. Lets call them CD1 and CD2 even though they have the same name. I put CD1 into my CD reader, launch disk utility, select the CD from the left hand window and then file-> new image and select the CD, save as DVD/CD master. I get prompted to enter my user password from diskimages-helper, and then it successfully completes. I open the saved image file and it only shows 5 files, not 6. I try that again and same thing happens. I eject the CD1 and put CD2 in my reader and generate a .cdr file. I open the .cdr file, and now there are 6 files, but they are from CD1, not CD2! I delete everything and reboot, and try again. It keeps creating an image file from CD1 even though I have CD2 in the reader!

Can anyone understand what is going on??? This is on a M1 Studio Max, Tahoe 26.5.2

Mac Studio, macOS 26.5

Posted on Jul 13, 2026 8:00 PM

Reply

Answer 1

Jul 14, 2026 9:10 AM in response to whodiini2

Remove all CDs and unmount all ISOs, CDRs, DMGs & sparsebundles.

Reboot the computer.

Try making the image of one of those CDs making sure to name the resulting file with a new distinct name.

Eject the CD when finished.

What do you have in the newly created image with a new unique name?

I would suggest doing this with Burn instead of Disk Utility (I've never had any luck with Disk Utility making images of devices or large folders). If you wish to try both, then I highly recommend following these suggestions before trying the other option at least until you can confirm the process works correctly.

Reply

Answer 2

MrHoffman

Level 10

160,587 points

Jul 14, 2026 7:42 AM in response to whodiini2

whodiini2 wrote:

No, the 2 cds have identical names. I am using CD1 and CD2 for clarification in this post. I can verify because I mount the image and compare that to the CD it came from and the files are different!

But this confusion does seem to be the intended outcome of two different CDs with identical labeling, though.

What happens if you burn a CD labeled CD5 with five files, and burn CD6 with six files? Then mount and test CD5 and CD6. Do things work?

I’ve chased deployment errors because the app developers decided to have two different versions of an app both labeled V1.2, too. The developers shipped their app V1.2, found a last-minute bug or whatever, and re-shipped another app V1.2 with differing contents without incrementing the version, and confusion ensued.

Reply

Answer 3

MrHoffman

Level 10

160,587 points

Jul 13, 2026 8:12 PM in response to whodiini2

Are CD1 and CD2 possibly mislabeled?

Reply

Answer 4

whodiini2 Author

Level 1

25 points

Jul 13, 2026 8:24 PM in response to MrHoffman

No, the 2 cds have identical names. I am using CD1 and CD2 for clarification in this post. I can verify because I mount the image and compare that to the CD it came from and the files are different!

Reply

Answer 5

whodiini2 Author

Level 1

25 points

Jul 13, 2026 8:25 PM in response to whodiini2

I tried a different app, called Burn and when it tries to save the image, I get an error. SO something is strange,.

Reply