This headstamp is one of the varieties that was made in Prague, Czechoslovakia rather than Schőnebeck, Germany.
Sellier & Bellot started making pinfire cartridges in 1870 and continued until the early 1930s. Based on the design of the boxes that this headstamp came in I would say it is earlier rather than later.
I do not think it is too scarce, though I have had less of this than other SB headstamps. It came in brass and copper for the 7mm ball round and it came in brass for the 7mm blank.
There is also a similar headstamp with a crown rather than the circle between the eagle’s heads.