Don't think that it is possible, somebody asked euss, from PS3Crunch (Dukio.com), and here was euss' response
Originally posted by another user
euss : You can however succesfully use OtherOS/AsbestOS /OtherOS++ to add unlimited (limited by the bootloader, in this example petitboot and hardware only) lets say 9999 different Linux/BSD installations.
euss : Oh, and in that explaination I completely ignore the fact of binded devices like the blu-ray, network etc. Otherwise you'll end up with errors like we had in the downgrader days with DRL errors because of timetraveling AACS.
euss : Besides the harddisk, you would also need to make a dualboot for the NOR/NAND + SysCon. Not very likely that someone would even put (the imo useless) effort into that.
*Censored* : It would be cool if somebody made a Dualboot fw like 1 for cfw (offline) an 1 for ofw [online].

its just an idea.
So looking at this, it doesn't seem easy, as in having 1 firmware cfw 3.55, and another one 3.60.
But if we have 1 CFW, 3.55, and 1 OFW 3.55, then that is more possible, but to have another OFW with 3.60 can become complicated.