The pipes themselves will serve as memory. :-)
a) create a regex operator stripping the colon and everything in front.
b) create a regex operator stripping the colon and everything after.
c) pass the string to both a) and b).
d) create a string builder for [input-from-a] + " - " + [input-from-b].
Tried sharing an example here: http://pipes.yahoo.com/pipes/pipe.info?_id=68b135e6b9a182a8bf9e1f329eaaf6f5