The exact count of Rajaraja's children - for that matter many later chola king's children - is unclear.
I've always thought that RR could have had more than one son. Kudanthai N. Sethuraman cleared my doubt. He introduces atleast one more son of Rajaraja. We are - rather unfortunately - unable to get the name of this son. Only his title is available : Gangai kondan - suggesting that he participated in ganges expetition.
Whose son is he ? We do not know - but Kundanthai suggests he might be panchavan madevi's son. With due respects, it is rather a far fetched assumption in my opinion.
This guy lived along with rajendra / rajadhiraja and was held in high respect and was ruling certain regions of chola territory. His son - again only the title is available - by name Alavandhan (!) - was given the pandiyan territory to rule and so on..
We know very little or nothing about one of rajaraja's daughter (madhevedigal) and even rajendra's daughter (arumozhi nangai)..
This is again a sample. There are many things like this in tamil history waiting to be uncovered...
I give below the information from an inscription from Thirumalavadi in Thirutchirappalli of the 29th year, 102 day of the reign of Rajadhiraja Chola - 1 which reads as follows.
"A pearl umbrella by Madhurantaka-devan Arumoli-nangaiyar alias Piranar, daughter of Rajendra-choladeva (was gifted)...."
Here we note the name of Arumoli-nangaiyar is prefixed with Madhurantaka-devan, probably to "further" indicate that she was the daughter of Madurantka-devan being another name of Rajendra Chola - 1
This "may be" for the reason to differentiate among two of them with same name of the same period, the other being being her brother Virarajendra's wife Arumoli-nangai.