The rarity lies in the waffenampts. From Jan Still
http://luger.gunboards.com/showthread.php?t=22701 :
The right receiver acceptance stamps determine byf 41 markings variations. They are as follows:
SE655 SE655 LTP reported serial range 4636o-4627ns (estimated production 120,300)
SE655 SE135 LTP reported serial range 4801ns-7491ns (estimated production 2,700)
SE135 SE135 LTP reported serial range 7478ns-1121b (estimated production 14,500)
"SE" stands for "stick eagle". "ns" stands for "no suffix". "LTP" stands for "late test proof".
If you have a SE655 SE135 or a SE135 SE135, you have a rarer variation than the SE655 SE655.
Jack