india evisa, indian passport not surrenderd

Hello,

Could someone advise me on this..Due to a family emergency we have to travel to india next week. both myself and spouse still got indian passport with ILR. Our son has british passport but we didnt get round surrendering his indian passport. Can we apply for evisa without having surrender the indian passport? would this be a problem..the online application asks whether he as an other valid passport do I mention indian passport on this?

Many thanks.