In the sidebar for a group we show members split into current members and former members. If a person was a former member for different time periods, we show a list of them. However if someone was a former member and also a current member, we show them twice. See the attached image, which is for Judas Priest.

Ideally we should show current members in the upper section, and also include their historical times. e.g. "Rob Halford (1973-1992, since 2003)", and don't show them in former members.