Why not, but we need help here...
We are ok to provide both GPL and MIT version of PlantUML in mvnrepository. And since we are somehow moving our source from sourceforge to github, I think we could both actions together (see https://issues.sonatype.org/browse/OSSRH-29501
However, I must say that I have no idea on best practice about double license software in github and mvnrepository. So suggestions highly welcome! Thanks!