I have been running both since my Rio car doesn't seem to like 2.0b7 as much as my Empeg car does, strange but true. My Rio car does have some other issues though and is currently at Cambridge getting, I hope sorted out.
Anyway I haven't noticed any problems and each have their own different icon so mixing them up isn't a problem, 2.0x has a green E and 1.0x has a player icon.