First user issues aren't as relevant in trade marks as in other intellectual property rights. Potentially you could have two companies in discrete markets/territories build up goodwill in an identical name with a dispute only being triggered when some form of encroachment occurs.

A good example was the Budweiser v Budvar saga http://en.wikipedia.org/wiki/Budweiser_Budvar_Brewery#Tradem...

Generally, you would hope that the parties could come to an agreement and enter what's known as a co-existence agreement where they just agreed to continue but in some cases agree not to further encroach on each other's markets for example.

The above example just ran and ran with each filing suits around the world, showing the difficulties of deciding who should have sole rights to a name when both have built up substantial goodwill over a long period of time.

Very interesting, thanks!

Yes. Think Apple. They weren't the first Apple, and they can't touch other Apple entities that have been around before the existence of Apple (ie. Apple Bank in NY). However, anyone that uses the name Apple, or a logo similar to that of Apple's, after Apple's original use, they can go after.

Side Note: trademark protection is more focused on protecting consumers than companies - unless the company has spent an excessive amount promoting and selling their products, at which point, they are given special protection/rights.

I highly recommend researching the Nissan Motors vs Nissan Computer case, as it covers many subtleties regarding names and trademarks