Point-to-point messaging is where one or more senders need to send messages to a single receiver.
There are two basic implementations of ptp messaging, the first is where the sender sends a message directly to a receiver, while the second is where a sender sends a message to a specific queue (which may provide delivery-guarantees).
See the diagram on this page: http://my.execpc.com/~gopalan/jms/jms.html
for a clear explanation.
In summary, yes ptp is the same as a message queue system, and yes you can have many senders.