Red Line on L at Chicago Ave, 2200's

Take a look at this pic - it shows (2) Red line trains, NB at Chicago, on the L. Further, one of those two trains is a 2200 set. Any ideas what's going on here?

http://www.railpictures.net/viewphoto.p ... 46&nseq=15

That right there is the result of a private "L" charter that took place this past Sunday - tooling around on the express tracks and changing the roll signs frequently.

Makes sense, thanks.