Both solutions seems to work, however there are caveats for each one given I wasn't very specific on the requirements.
new data set:
10a textile
b10b wtf
b20b omg
b20b woot
20b teasdf ha
20b...
I've looked at the join command which is able to perform what I need on two rows with a common field, however if I have more than two rows I need to join all of them.