Is this an expander coating for YAG? I see lots of different coatings on their web site, but many of them made for 1064 nm have some curves which allow them to be used in the VIS, at some wavelengths not optimal, but usable, better than without:
Look at that one near infrared coating curve which dips low at both 532 and 1064 nm, that's what I'm talking about.
I bought some IR beam expanders for 1064 nm, not 532 nm, but when I later came across some 1064 nm infrared expanders which had a slash 532 nm marked on them I measured the loss through one of mine at 532 and it worked, low loss.
If you see a beam expander on ebay for 1064 nm, I wouldn't necessarily expect it is good at 532, but my bet is more often than not it will be. I Don't buy guessing, I get the part number and try to find specs.