This happened to me few days back. I referred one of friend to Company A and he got an offer there. The very next day he got an offer from Company B with more package. He was confused to make a decision. I advised him to think on a long term benefit and decide accordingly. He accepted the offer of Company B and joined them. Meanwhile I was repeatedely telling him to inform the same info to Company A but he was not doing that. Till date he has not done that and ultimately I lost my name and image with Company A since I was maintaining a good relationship with them. Now, they are not going to encourage any more candidate of mine. With this kind of attitude one may hamper other candidate future as well. I would suggest there is no harm in explaining the real picture and your situation so that you maintain a good relationhip for who knows tomorrow you may get even better offer from Company A as well.
