Constant Content

If I have an article that would fit more than one request can I offer it to more than one requestor at a time?

If not, how long is an appropriate length of time to wait after submitting to one and not hearing anything, before submitting to another?

Yes, I think it's fine to offer it to several requestors at the same time, as it's a case of 'first come, first served.' Why not double your chances of a sale?