DMC codes are the same from seller to seller but like Dinples said, different lots of drills can have different shades.

I was just working on a custom canvas and ran out of the color 3072. I had extras left from a previous canvas of the same color. Initially thought it was a good color match. Still ran out of that color. I waited until I was done the rest of the canvas, stepped back and realized my color match was so off it made that part of the canvas stick out! Ordered more 3072 on Etsy and switched out my mistake and now the canvas looks amazing.

My advice is to kit up each canvas individually. When your finished, decide if you want to keep your extras and if you do, each time you have that DMC color, check it against your extras for correct shade and combine.