Havent tested so dunno bud.
But its kinda useless because you already have 2 different .cfg files so why not just bind mouse5 like.
1st.cfg -> bind mouse5 exec 2nd.cfg
2nd.cfg -> bind mouse5 exec 1st.cfg
Or, I think you could actually just bind mouse5 "exec 1st.cfg; invnextnongrenade" - to keep the already existing command there as well.