Hello, i hope you are good !
I would like to achieve that all these distances are equal and fairly close to the length I have defined. I am a bit lost. Thank you very much.
You want to split this polyline in line segments with equal lenghts?.
Or do you want points placed on the polyline with eaquel distance.?
Is this polyline one curve for you or two seperate line segments with different lenght.
So many questions and no file.
And the points on the two curves schould have the same distance to each other started from curves endpoints and ended at curve endpoint.?
Yes !!!
Is the smaller curve lenght a multiple times the larger one …otherwise your goal isnt possible.
Curvelength/point Distance = how many possible points if the number is integer…round up or down.
Curvelength/possible point amount …integer. = possible exact distance.
The sum of the point distance has to be your curve lenghts.
but how you would do to have different curve ?
5/0.8=6.25 round down 6
3/0.8=3.75 round up 4
5/6 =0,8333…
3/4 =0,75
0.83-0.8 = 0.03
0.8-0.75 = 0.25
You see not possible
but 0,8 its not a problem its change by a number who is close to make that possible 
One curve needs to be the multiple times the other.
Curve 5 m
Other curve 0.5*5=2.5 m