Why there are two device tree binaries for Vybrid based modules?

It seems there are two device tree binary for Vybrid based modules:-
vf500-colibri-eval-v3.dtb and
vf610-colibri-eval-v3.dtb.
Which one is needed for flashing.

Two variants are available based on NXP/Freescale Vybrid SoC one is Colibri VF50 and Colibri VF61. There is no need to manually select the binary blob, during flashing update scripts will take care of selecting appropriate device tree blob. One need to just prepare the flashing media(SD card, USB flash disk or tftp dir) and use it while flashing.
More information/hints regarding flahing refer this article.

Actuall vf500-colibri-eval-v3.dtb and vf610-colibri-eval-v3.dtb.