wrong stationing on alignment with offset in euler spiral

[office]

Hi,

I'm getting strange results on the stationing of an alignment with an 0,62m offset:

In the area of an klothoide (Euler spiral) i create two points, the linear distance is for example 12.500. But when i run an station inquiry on those 2 points and subtract the stations i get as result 12.4988. If we take it for granted, that a line is the shortest connection between to points something is obvious wrong?!

So i recreated an alignment as if there is'nt an parallel alignment:

This recreated alignment is created with the same R and A but differs in the lengh of arcs and lines... Even when i messure on this alignment i get this strange results.

So my question: What's wrong with the stationing in euler spirals? (or even with me *g)