Zone ke andar divisons ke bich coaches ka idhar udhar hona bahut common hai..Nothing to do with DNR or DDU..Zonal HQ ka order aaya toh coaches idhar udhar honge hi..No officer withing a zone make it an issue (unless and until the coach being received is unfit for maintenance ),jaisa aap bana rahe ho.
Secondly 12309/10 is the most important train of ECR..It will always get the best coaches among the lot.