This is in respect to what happens when there are TIES in bids or offers across characters or accounts. And I'm changing my statement to "I'm not sure" based on my experience with common salvage.
Often I'll have lots and lots of bids out at a low level that happens to be the highest outstanding bid, so when someone comes in to dump salvage, I'll have the best bid. On a single character, I've noticed that bids get filled in what seems to be a random fashion. A few here, a few there. When I use the same bid across characters, I notice that sometimes one toon's bids fill entirely while another's don't. That may be a timing issue or an observational error though.
On the sell side, I will frequently dump large amounts of common salvage at 1 inf. Since that, by definition, is the lowest outstanding bid and guaranteed to be at or below any outstanding bid, I would expect them to sell instantly or close to it. However, sometimes the system doesn't process my offers instantly, and I'll often wait 10-15 seconds between sales, despite the fact that there are plenty of outstanding bids. I am guessing that is because there is at least one other person selling at 1 inf at the same time, and that the system is somehow allocating our offers in a manner that neither seems random nor in order of when the order was placed.
It's curious.