As Ken said, lots of instruments from around 1900- are labeled Stainer but they're really just German shop instruments. I have a violin from my great grandfather which is also labeled Stainer but it was purchased in Germany from a shop new from around 1880.
Here are photos of the "Stainer" 1645, Absam bass.
http://www.musikland-tirol.at/images...tainerbass.jpg
http://www.musikland-tirol.at/musiki...ss-detail.html
As you can see, the level of quality in this bass is not exactly the same as your instrument. But that's okay.