sorry, I cannot help here - I cannot imagine how QlikView would recognize that - but I have the same issue and would be interested if there was a solution.
Do you have two separate charts? Why not just use a combochart?
=> Maybe you could set one of the two overlapping whatchamacallits to display the value only if the other value is not within a certain range of it (that range would depend on the font_size)? In that case, you would, in certain cases, have only one of the two values displayed, but it would avoid the overlapping.
I'm actually facing with the same problem, and finally I decided to show values only for an expression. However I'm already in trouble because I would like the user to see the values on the pop-ups but the labels are not visible. This labels for the expressions are calculated labels, such as =max(Anno) and =Max(Anno)-1, while there is a third label (not calculated) that is simply BUDGET. do you have any idea why the calculated labels don't work?
I don't see how putting it in segments will help (except for the specific example where the line is above the bar). If the line for some reason crosses the segment next month, you could face the exact same issue with overlap, or?