In a modern jet (ie, not a 737
) there is no issue with two VHF sets being on the same frequency. When you switch to approach or tower, the radios get a little louder and you can hear the other bloke/girl transmitting. Much more preferable than having to listen to ride reports or wheelchair requirements during such a critical stage. What if an ELT went off during flare or at V1?
If your SOPs require 121.5 on 2 at all times then I would be deselecting that audio below transition.