I had a similar situation, but I was not the shadchan. It was my son that got engaged. I asked my Rav what one does when someone suggested a shidduch, gave us the info, but somehow it didn’t seem interesting. A few months later someone else brought it up and it worked. My Rav said that if the second shadchan thought of it on his own then he is the only shadchan. If not, the first shadchan gets 1/3 and the second one gets 2/3. In my case the second shadchan did know that the shidduch had already been suggested and decided to bring it up again.
