Not at all, MZpalmTree. I've actually spent the morning feeling bad about it!
It's probably not quite as bad as it sounded in my initial post:
Offer 1 was rejected and a counter proposal was put forward by the Seller. I rejected this.
Offer 2 was made via Fidelity after I rejected the Offer 1 counter-proposal. They appeared to be closed all weekend and were slow to respond.
Offer 3 was made whilst I was waiting to hear from Fidelity and after I'd rejected the Offer 1 counter-proposal. This offer was made through the agent who'd offered to make multiple offers on my behalf (so I don't feel too bad about that.
Whilst waiting to hear back on offers 2 and 3, the offer 1 seller came back with a series of counter-proposals. I rejected them and explained I was waiting on Fidelity. The offer 1 seller then accepted my original offer in an attempt to close the deal. I explained that I wanted to wait to see what happened with Fidelity first.
So, I don't think I did anything wrong as regards the Offer 1 seller. I feel bad for the Offer 2 seller as they responded really quickly and accepted my offer without making a counter. It was their agent that suggested it was OK to make simultaneous offers though. I won't be doing that again.