Hi Peter,
What I meant was, that, Si wa panj and Si wa Shash are seen in both dams and damris because the dams and damris of those 2 dates do not have persian months on them.. However, the dams of ilahi 37 are known in all 12 months, so the si wa haft damri just discovered seems to occur only in damris and not in dams. Hope I'm able to make sense.