We see that here, and people will often contact more than one TD, one MP, to try to resolve their problems, and since a lot of that now takes place by email rather than by tramping along to a local constituency office, it's fairly easy to blind-copy all the TDs in the constituency into your request. I think TDs know that this request may have gone to another one, so they'd better deal with it.
There is competition both within and between parties to be seen as a good member of Parliament.