As a previous poster said: Pursue all nomination sources until you have an appointment. If an MOC, staff, committee ASKS if you have another nomination, LOA, whatever, you must, of course, tell them. If they don't ask, you don't need to volunteer that information. Many share information, some TRY to share information, some do not. That is not for you to worry about.
Son had nom from Representative two years ago. Senator's office told us they share information. That was the last we expected to hear from
Senator. Then, unexpectedly, her office calls, tells him he has her nom as well. I (Mom) inquired later and was told that they try to share, but some congressmen never bothered to tell the Senators who they nominated.
You cannot count on them to share, or not to share, or to do what they tell you they expect to do. Pursue all sources for nominations until you have an appointment and be honest with all questions you are asked. Don't try to do their job or give them information they may or may not want or need. Some of these people have very experienced staff members and committees who handle all this. Some have brand new staff and committees. Pursue all nomination sources until you have an appointment!