yes you can wire up more then one piece of heat tape to one electric source. all you do is wire up the first one normal at one end and on the other end you wire it up to the next one and so on. It will kinda look like this. Sorry for my lame blue print lol.

+------(====)------(=====)------(=====)

+ = Male end of a power cord
--- = Power cord
(===) = Heat tape