Is it possible that isomer Meta Chloro Aniline devoleps during
reduction of 2,5-DCNB for manufacturing 2,5-DCA

If you want a precise answer you'll need to explain a little first.

1.) What reagents are you using?
2.) by isomer meta chloro anilline, you mean 3 chloroaniline.  as in 1
chlorine, the other two removed?

Just as you've described, IMO, it would be pretty hard to happen under
normal conditions.

We are adding Thiourea as a catalyst and yes it is 3-Chloro Aniline
which is being developed during reduction.

ok...now you've piqued my curiosity.

i haven't got a clue, but here's where I would start.

first, get said spectra on putative 3-chloro aniline:  proton, c13,
ms(cl's will be a dead giveaway).

a.) make sure indeed that starting materials are what you think they
are and apply all common sense.

b.) the ortho chloro's on 2,5 dcnb are quite reactive to SNar
substitution. (As in alcohol + cook=ether)

c.) I would think more likely you get thiourea addition-elimination to
one of the chloros then reaction with the reduced nitro. (think
nitroso, amine, etc, think amino benzathiazole)

Now you just gotta blow off half of that heterocycle to get 3 chloroanilline.

chugs,

I'm sure 15-N tests would prove you right :)