I agree the easiest way to tell is the middle white band. If it runs up into the top fin it's more than likely a sebae. If not, its a clarkii. Unless you see both, the differences are hard to spot initially. Yours looks like a sebea, IMO. Never seen one orange colored like yours though, but colors vary. Their body shape is a bit different also, the sebae is more "slim" from top to bottom, the clarkii is "thicker". For lack of better words. I have had both, and honestly each didn't care if they had a $5 anemone (from the wrong ocean even) or a $50 one. They were not picky at all IME. Also agree with why they are fighting, just keep an eye on them. If it gets nasty (fins torn and such) you may need to seperate them.
zanoshano "
they do look kinda similar thogh, but ur lfs should still know what they are sellin you.
" They should, but don't count on it. That is why this board is so helpful....soon you will know more than your LFS and just scratch your head as to what they are thinking.