Tobia Scarpa for Knoll Bastiano Dated 1961 Knoll International  

the knol international site has this text

With the 1968 acquisition of Gavina, the Bastiano Lounge collection was introduced to the Knoll catalogue. The simple, comfortable design worked well with modern and traditional interiors alike and was one the most successful products of that time period.

best regards maarten

Is it at all possible that the faint, smudged ink stamp actually reads "1981"?

Overall condition, label, and/or fabric might be clues. Also, if you unzip upholstered covers, you might find a "law label" attached to cushion inserts that could help.

Thank you for the suggestion, I am going to check the cushions, One thing strange is the label is the Knoll international label that was not made until 1969 so I have to do some more research it must be smudged in a way that makes me see 1961. Will post in a few if I find the other label.

They say that we sometimes see what we want to see. I only wish that were more often the case...

Best of luck. Nice sofas either way!