Since jkdefrag v3.11 unfortunately no more.
Can you tell me more? If you want to run 3 copies simultaneously then simply make 3 copies, all with different names. I haven't tried it, but it should work...
I have here jkdefrag.exe, jkdefrag311.exe (both version 3.11) and the older versions starting from 3.7 in each case than jkdfrag3x.exe. Everything in a folder.
If I start only jkdefrag.exe and afterwards jkdefrag311.exe, so gibts with Jkdefrag311 in the log only [ i]12:45:42 I to already running: JkDefrag.exe[/i ]. Hmm thereby notices to me now that for the log the standard file name (jkdefrag311.log) is used and not into the commandline indicated (-l "E:\JkDefragGUI\jkdefrag_z_004.log").
An older version after or forwards jkdefrag v3.11 is further possible, not v3.11 several times.