Yeah, I'd be annoyed. Though I'd also be irked if the Grass starter ended up as mono Grass again. But I guess as long as at least one of them has a decent design I won't mind too much, I don't pick my starter based on type alone, there are other things that could make up for it.
If it was a cool design then I'd get over it. But I'd rather not have the same type combo again. As it is, I've become increasingly less fond of Fire starters as each Gen goes by. The Water starters have always been average to me, with Piplup being the one I like the most, but I do like Squirtle and Mudkip a bit too. Grass starters have been my main choices as of late, and by that I mean Treecko and Snivy as Turtwig I never plan on ever using.
Another fire/fighting starter would mean gamefreak has ran out of ideas. Trust me
They already have. Gen 5 holds the dubious honor of being the first generation that didn't introduce anything that couldn't have been implemented in the previous one. Most of gen 5 mons are rehashes of gen 1 ones as well.