BR3104852: only warn once for repeated prefixes
BR3104852: only warn once for repeated prefixes

techkey/nasm,techkey/nasm,letolabs/nasm,techkey/nasm,turingstudio/nasm,turingstudio/nasm,techkey/nasm,letolabs/nasm,letolabs/nasm,projedi/nasm,Distrotech/nasm,Distrotech/nasm,turingstudio/nasm,projedi/nasm,projedi/nasm,projedi/nasm,turingstudio/nasm,projedi/nasm,Distrotech/nasm,Distrotech/nasm,techkey/nasm