Just wondering if this is possible with imgburn?
I have a high spec PC so performance shouldn't be an issue
Yes this is possible.
Just open a second instance of ImgBurn to do the burn with the other ISO. ImgBurn will open, detect that the first burner is busy, and will only allow you to burn with the second burner.
I've done it. It's possible. However, If you're burning a really high data rates like 8x Blu-Ray burning even a very capable PC may not be able to keep them both happy even with Imgburn using 512MB of RAM for cache for each.