My team is working for the same POrg and PGroup and we are having trouble with division of work. As we know, error messages are shown when someone else has processed the same PR we are trying to process or are currently processing it at the time. But how do we avoid this altogether? Is there any flagging method we can add to tell others we are working on a particular PR so they don't have to open the PR to receive the error? This will help increase efficiency and saves a lot of time, especially working for a global company.
Impossible to avoid processing same requisition if you are using same purchasing group for all purchasers.
I think better if you are making purchasing group for each purchaser and separate materials to some purchasing group. So, each purchaser have clear responsible.
If you are using quota arrangement and source list then you can using tcode ME59N (by background job) for create PO from PR. PO also can send to vendor automatically if you are using output type which support for this purpose. This method is very efficient because no need create and send PO manually by purchasers.