We currently have two tags that, in my opinion should be synonyms.
I think marker and markers are identical. Does anyone object to them being merged? Or is there another definition that I'm not aware of?
I suggest making markers the master tag as it is tagged on more questions and has a more complete definition. Further, it seems our tendency is to make the plural the master and the singular the synonym. For example join is a synonym of joins and domain is a synonym of domains.