different size in "merge" and "previously been interviewed"
I am a new user of understanding society, so pls apologize if my question is quite basic.
I am trying to merge the wave1 and wave2 data, i.e. merging "b_indresp.dta" and "a_indresp.dta". Using merge function in stata (the stata code is 'merge 1:1 pidp using ... '), I found 38388 participants were both in wave1 and 2, 162019 were new entrants in wave 2 and 12606 were in wave 1 only. Then I look at those who have been interviewed before, by 'tab b_ff_ivlolw', I found 46164 individual had previously been interviewed. This is bigger than 38388 I obtained beforehand.
Do I miss something here or misunderstood with the b_ff_ivlolw?