[Chimera-users] Chimera launches multiple instances on Mac OS X Catalina

Hi, After upgrading to Mac OS X Catalina, Chimera now launches a new instance of the application every time I open a new file. Previously, if I for example double-clicked an MRC or PDB file, it would open in the existing instance of Chimera; Now, it launches a new instance each time, which pretty quickly leads to me having 20+ copies of Chimera running simultaneously. Has anyone else encountered this and found a way to revert to the original behavior? Cheers Oli