Switching jobs between PSUs without NOC.

This query I am asking on behalf of my friend Sumit. "Sir, currently I am working in a PSU, let X for last three and half years. I am a permanent employee and have completed successful training and probation period. However, the bond period in PSU X is 4 years (3 years after 1 year training period). Few months back I had applied for another PSU, let Y, which offers a lesser pay scale than my current job. I intend to work in PSU Y only because I will have a better personal and family life there. I have not informed while applying that I am employed in a PSU, since here in PSU X, getting a NOC is almost impossible. They keep on rejecting any such applications with or without giving any reasons. This has been happening and many of my colleagues have suffered due to this. Based on this, I have neither informed PSU Y that I am employed in PSU X, nor I have asked for NOC from PSU X. Now, I am selected in PSU Y. I intend to join PSU Y after proper resignation and relieving from PSU X. I will even have to pay bond amount as around 5 months are still left in my bond period. But even after joining PSU Y, I don't want to disclose my service at PSU X as I had not informed them while filling form and during the interview. Sir, I just want to know that if I proceed as intended, what may be the problems later in PSU Y if they somehow come to know about my previous employment in PSU X. Also, can PSU X may be a problem in future." Need help.Thanks in advance.