Yes, I know that that is a bad Idea, and two different antiviruses are interfering each others and my cause therefore system hangs and bsods. I was looking for a current antivirus database/signature for (Free)DOS nod32 (nod32.000), and thought, that I may got the database by installing it on Windows 10, but they changed the database layout. I disabled nod32 modules, to decrease the possible interference. I'll remove nod32 soon.
BTW: ClamAV is still an option for DOS, or one have to use outdated scanners. F-Prot 3.16b for example. Unfortunately F-Prot also changed it's database/signature layout. An older version of F-Prot still gets current signatures(!). I don't know if there are NEW DOS Viruses in the wild, though.