In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
On the first occasion no semen was found which means this could be just a dream. The wetness experienced on the second occasion was also not due to semen. Therefore wudu will suffice.
And Allah Ta’āla Knows Best
Mufti Saeed Ahmed Golaub
Islamic Solution
Jamaica