There are as many reasons for two men to want to share a room as there are reasons for two men to be on the same airplane. However, on the chance that your reason is that you and your travel companion are a couple, you might want to check out the GLBT Travelers forum here. A quick search for "Oman" there turned up these threads:
GLBT travel to Oman
Gay Oman
Gay in the UAE? Beach etiquette?
None of them is particularly encouraging, but none is from within the past year or so either. You could do a more thorough search than I did and/or post your question there.