I was having a discussion with an ex-yeoman here at my civilian job, and we looked in the awards and uniform manuals and could not find the answer...so here is the questions....
if a person has both active duty and reserve Good Conduct medals, does the member wear both or just one, if just one, which one. If the member is currently a drilling reserve.

You can wear both, with the Active Duty GCM taking precedence over the Reserve GCM.

Enclosure 22 of the new Medals and Awards Manual lists all of the medals and ribbons in order of precedence authorized for Coasties to wear.

Thanks..will have to smack him on the head on Monday..