How to combine last column entries on the basis of common first and second column in R

Question

The input file has three columns V1, V2, V3 I want to combine V3 because of common V1 and V2, Please guide me how can I do this in R.

V1 V2  V3
1 ARG  N2_l,RC_e,RC_t,N3_l
1 ARG  N1_l,N3_l,N2_l,RC_t
1 ARG  N1_e,N6_e,N4_j,N3_t

out put needed

1 ARG   N2_l,RC_e,RC_t,N3_l,N1_e,N6_e,N4_j,N3_t 

Thanks