Depends. For Example, If you apply the classifications inbound to an interface on a switch, then the DSCP will classify them according to your wishes. If you change one switch and then leave the old classifications on the other switch, each will classify them differently. Will this cause a problem? Probably, depends on what your using it for. If you use it to determine which packets come first to last when processed, it could misclassify the packets and lead to "undesirable" slowdown for any real-time traffic you care about.
