My guess is that all or most could be reprints or fakes (?) Most original Tibetan stamps go for big $$.
On the other hand, with such a low bid, if you can get them for a few bucks then go for it. Some stamps that were issued in 1934 could be original but according to some of the scans of the lot, the colours do not match the catalogue listings. This is what makes me think that some of them are reprints (?)
I have won a couple of lots from the same seller and he is a good dealer if that helps.