I have some doubt. I made a test on 1 actor (Diana Rigg) and on the 11 selected items, the signature is always very different (in particular the first letter D). This is very surprising and I would not trust these autographs. I tried the same on 18 signed items by Glenn Close, and the same can be observed.
Now unless these 2 actresses are particularly unstable, I would not trust these. But maybe somebody more competent than me will not agree...