Yes, British Rail found this out when they were testing the new Class 91 electric engines using Mk3 carriages. The Mk3 needed a different power supply system as provided by the Class 43 engine so they kept 1 attached for hotel power, but soon found out they started having exhause fires, so they had to run them at load as well during testing. There is a video showing this bad arse hybrid with a poorly maintained 43 in the front.
https://www.railforums.co.uk/threads/class-91-43-late-1980s-formations.141904/ - technical discussion here.