Yes that is what was happening. In the case of Brent/Gasoil spread, the entry price was showing a figure of 600 or something like that, and the last price(bid/ask) was showing the actual Brent crude price of 45 or so at the time. Thus creating an enormous profit immediately.
Does seem to happen a lot on demo accounts, giving a false illusion of profits. I can't work out whether it is deliberate on some brokers part, to draw clients in, or whether it is as you say simply system glitches.
Trust me, it is just system glitches. The brokers are not out to get you. They want you to be profitable in live, not profitable in only demo. Demo makes them no money, live does. The longer you are profitable in live, the longer they are profitable. If you blow out and close your account, then the broker makes no more money. It really is that simple.