Understanding Society User Support

Hello,
From my understanding, b_mvever and b_mvyr refer to new entrants only; however, some people who have data on these also have a valid value in wave 1. Can you explain why this is the case?
Many thanks in advance!
Carolina

tab b_mvever a_mvever

lived at |   lived at address
     address |      whole life 
 whole life  |       yes         no |     Total
-------------+----------------------+----------
         yes |       210        211 |       421 
          no |        89      2,389 |     2,478 
-------------+----------------------+----------
       Total |       299      2,600 |     2,899