The issue needs to be exmained on various aspects.
Bigamy is an offence under IPC, and it remains an offence despite consent of your first wife. Off course, you cannot beprosecuted unless until a complaint is filed by the first wife. Thus as long as consent remains, yu wil not be prosecuted. Just that any day she decides to file complaint against you, anytime after marriage, she can file and her previous consent will not be a defence.
Under Hindu Marriage Act, such marriage is not a valid marriage, irrespective of your wife's consent. The effect of this provision is that the second wife will not get status of wife, in terms of property rights, maintenance rights, legitimacy of children etc.
There are other Acts also prohibiting bigamy- conduct rule of government servants. Thus if you are subject to those rules, desciplinary proceeding against you, under conduct rules can be initiated irrespective of consent of your wife.