Extra entries getting inserted in category table when an installation is updated

Repeatedly hit /rest/registry/device endpoint with following load

{
"deviceToken":"q1wSEk8BiQOGwOCVnbJnt1wSEk8BiQOGwOCVnbJnt1wSEk8BiQOGwOCVnbJnt1wSEk8BiQOGwOCVnbJnt1wSEk8BiQOGwOCVnbJn",
"alias":"23425@xyz",
"categories":["offer"]
}

Notice how extra entries are getting created in category table. I suspect this leads to problems later when we try to update an installation with alias change