Sales by Item report is double counting invoices with multiple payments..??

I have a service product for 30 Min Training.  We recently sold 53 of these, and I have those invoices in QB accordingly.  When I run my Sales by Item Summary report, though, I see it showing I sold 56 of these.

When I click to view the details of these 56, I see that some names are showing up twice on the list, and it shows the same invoice number for both.  

When I look at that invoice, I see that it only includes this service item one time, but the invoice was paid in two separate payments.  Shouldn't be a problem.

When I look at the Sales by Item report, though, this single item is added twice on the report, and it looks like I sold one more unit than I did.

Here's a screenshot of the invoice:

The Brian Pace Training:30 Min has a single unit added on this invoice.  The invoice was paid in two payments:

Then when I look at the Sales by Item report, it shows up twice:

The same invoice number, same date...two separate lines showing 1 unit each.  This reflects in the total at the bottom of the report, and makes it look like I sold an additional unit than I actually.

ADDITIONAL INFO

Upon further review, I notice that when I actually count the QTY column up for this Sales by Item Detail report, I end up with 59:

So my paper records show that I sold 53 of these things.  I'm trying to reconcile that against my QB reports, but the Sales by Item reports show 56 even though I get 59 when I count it out myself.

That said, John is on there twice, and Ray is on there three times.  So that's 3 additional units between the two of them.  If I subtract those 3 from the 59 I'm counting, then I do get the 56 that is displayed on the report total, but that's still 3 more than I actually sold.  I'm super confused.

Any information about what's going on here would be greatly appreciated.  Thanks!