I found refocusing blue helped a LITTLE - but it does not remove it. ALL the Taks I have had do/did it, EXCEPT the FSQ-106ED (yes, the N's all do it). The FSQ-85 certainly does do it.
FSQ-85 image:
http://www.astrobin.com/full/119145/B/
FSQ-106ED image:
http://www.astrobin.com/199796/0/
FC-100 (OLD) image:
http://www.astrobin.com/full/176758/C/
The last one is worth looking at all the revisions, showing degree of blue flare through this doublet - and the ways I tried mitigating it (depends on the stretch of each channel)