Results showing browsers not reusing existing open connections

My test results are showing browsers are not reusing all of their existing open connections when talking to the same destination. For example I see anywhere between 8-15 connection requests to one specialized content server and only 2-3 of those connections were reused later. So, it can’t be that the browsers are reaching their persistent connection limits.
Anyone else seen this? Better yet, anyone know where the problem lies exactly?

Have you got a test we can look at?