Really thanks for your keen interest.
That would have been the next step... I figured there must have been a mistake in your bitcoin.conf, so you were running bitcoind on the mainnet, but using the testnet ports... This way, you wouldn't be able to start the daemon on the testnet, since the ports were already bound...
It's perfectly find to have 2 conf-files: one for the main net, one for the testnet... If you do this, you can avoid having to start bitcoind -testnet, but if you do this, you'll have to add a parameter passing on which config file to use