Without getting into a classified realm, RWRs are programmed based on collection of radar parameters from different sources.
saying a radar has been upgraded for better range, still means the same RF/PRI parameters, it just has more power.
a better detection capability will mean modulation on the pulse. However, older RWR systems may not have the capability to detect this modulation and therefore look at external parameters only. Hence why variations of a radar on jets will show as the same symbol.