Can voice test affect the MOS if done at same time in 2 separate phones

3G / 2G
,
1

Dear experts

we use 2 UE one for MOS test and the second for Voice calls at the same scripts
my question is , is there an impact on 3G MOS result when the second phone use 3G voice calls . (2 UE at the same position , same cell, same freq and SC)

thanks