[Users] Why is a second RPID header created when I do two subst()?

I have two problems: 1. I am attempting to clean up my Remote-Party-ID header so that my Polycom UAs will display the incoming number as a number rather than as a URI. This requires the domain to match that of the UA's server (e.g. siptest.columbia.edu). And, I want to rewrite incoming calling numbers from my PBX to be in 5-digit format and other US 10-digit numbers into proper E.164 format since my PBX and at least one of my ITSPs doesn't provide them as E.164. So, I do a couple of subst() operations on INVITEs. What's wierd is that one Remote-Party-ID header becomes two when it gets to the UA. The call flow is: INVITE r-uri <sip:10508@128.59.59.96:5060> from <sip:9174147124@128.59.59.242> rpid <sip:9174147124@128.59.59.242> Here's the code for the route block: route[10] { xlog("L_INFO","route[10] $ci: method $rm r-uri <$ru> from <$fu> rpid <$re>\n"); # first just clean out the domain name subst('/^(Remote-Party-ID:.*<sip:.*)@.*>(.*)$/\1@siptest.columbia.edu>\2/'); # now strip our numbers down to 5 digits subst('/^(Remote-Party-ID:.*<sip:)(\+)?(1)?21285([134][0-9]{4})@/\1\2/'); # expand 10-digit NANP numbers to E.164 subst('/^(Remote-Party-ID:.*<sip:)([0-9]{10}.*$)/\1+1\2/'); # XXX dip the calling name database XXX # ??? xlog doesn't show the result of rewriting it. # xlog("L_INFO","route[10] RPID is now <$re>\n"); xlog("L_INFO","route[10] $ci: RPID was rewritten.\n"); return; } #end of route[10]