Indeed they can but their scaling is not that good at all.Also I found only one model of 6950 under 200$ in egg.
Who cares about scaling when GTX560Ti runs out of VRAM in modern games such as SKYRIM, Max Payne 3, etc. and is really not that fast to begin with. You can add 15% more performance and it will still lose.
Bulletstorm 1080P 4AA
HD6950 2GB = 58.8
GTX560Ti = 44.6
Serious Sam 3 1080P
HD6950 2GB = 47.9
GTX560Ti = 38.3
Old Republic 1080P 4AA
HD6950 2GB = 61.5
GTX560Ti = 37.4
Anno 2070 1080P
6950 2GB = 35.6
GTX560Ti = 27.2
Batman AC 1080P 4AA
6950 2GB = 43.6
GTX560Ti = 35.6
Witcher 2 1080P
6950 2GB = 44.0
GTX560Ti = 34.6
It's not surprising since GTX560Ti has never been a better card than the 6950. In cases where GTX560Ti does well, it comes close or barely beats the 6950, but when 6950 leads, it's smokes the 560Ti 1GB because newer games want more VRAM.
Even in this head-to-head against a GTX560Ti AMP! (950mhz), the 6950 1GB still won:
"On the performance front, the Radeon has a slight edge. The AMP! Edition is faster in a few scenarios, but the Radeon offers higher frame rates in more games." ~
TechReport
And despite losing, the GTX560Ti manages to use more power.
It's even harder to make the case for the GTX560Ti now since games are starting to use more than 1GB of VRAM.
At the $180-190 level, I'd get neither the 560Ti nor the 6950 2GB. I'd add a bit more for the 7850. But I still can't recommend a nearly $200 card with 1GB of VRAM under any circumstances.