If not, what steps are required to get them certified?
When an appraisal is planned and submitted to the SEI an "organizational
unit" is defined. That means that the group at your site(s) within that unit ("software," "Java Projects"...etc) can claim to be CMMI ML2. So if the other group consists of some teams in
the same location, or in the same "unit," then yes, you could "claim" to me CMMI ML2 . But if they were, for instance, at another site, or something other than the organizational unit, you would not.
If you wanted another site or group to be ML2 you could save a tremendous amount of
time and money by having them adopt your processes - then you could simply
have an appraisal conducted either on that site, or on both your sites
together. But beware . . . it aint so easy to deploy processes that other people use.