Yes, if it's not a solid copper sheet don't anneal. 

Hard to tell in pic but does look like a multi-layer sandwich type?

My money's on that being a raised 'lip', hollow underneath.

Looks like, on quite a few models, Yamaha went from a flat gasket to one with the raised lip stamped into it - presumably the crushing of the lip was deemed to give a better seal. Have a look at the variations of part number 214-11181 on CMSNL to see what I mean. Yamaha did the same thing with the DS7/R5/RD250/350 head gaskets.

If I'm right, then ok to anneal if required.

Yes, the later gaskets were solid, not sandwich.  But with aftermarket, who knows what they did?

I never thought about any difference in sealing ability...  both seem to seal great.  I always thought the "asbestos sandwich" type was use to inhibit heat transfer from the hot cylinder head to the somewhat cooler cylinder?  That's my guess. 

A lot more expensive to make a "sandwich" gasket and from what I remember reading decades ago in SAE papers, probably not worth any minimal benefit, though if your engine had a sandwich type I'd recommend staying with it if possible.

 

The ones of old I'm talking aren't multi layer but just thin top bottom & rolled over the filling. Op I think said feels flexible or words to that affect without looking back. Just be careful that's all. Also by memory of old you can't see the filling as its rolled over in every direction even the 4 holes for the holding down long nuts. Go on cut it in half for a look--na don't do that!! But I might if I can find an old one. Ps not talking multi layer peel apart to raise compression although that'd be a trick if they made gaskets like that. Think bsa gold stars had that to get the squish right. What's a bsa you say haha--never mind. I could never afford one anyway.

If any cares, here's a photo of it. Outer layers of copper with, I guess, asbestos in between.

flic.kr/p/2pS7uGi

Yep that's the one. Just grease & refit is what I do. Or just refit same way (direction) it came off as I'm sure I remember originals covering a bit more area forwards between the bolts I guess being the exhaust side more Heat I don't know. Might be dreaming.