Yet another merging lists question but different

We have a case where some customers will send us orders on Excel. Each order *may* have *some* duplicate items. We then merge the two lists to get the total qtys of *all* items ordered. Sometimes the orders can have over 100 items.

The way we're doing this now is very manual and I can't help but think there's an easier way in Excel. I've read some of the other Q&A on this forum and found similar questions but nothing that really applies to our need to merge data with *multiple* columns.

The way we do it now:
1. Receive Order1 July.xlsx and Order2 Oct.xlsx from our customer. It's two separate orders with some duplicate items that are scheduled to ship on two different dates.

2. We then copy-n-paste all the date into an "intermediate" spreadsheet intermediate step.xlsx and manually line everything up. We use the Exact() function to help line up everything.

3. This end state.xlsx spreadsheet is our ideal end state, where we can see all the items ordered and get a total qty for each item.
The two columns that show the qtys ordered for each month is useful but not mandatory. If we could just get something resembling this "end state" with at least a total qty, we'd be happy campers.

Any suggestions on an easier/more automated way to get there?

Thank you, humdingaling! I think I can follow your sheet.

1. I took my actual July info and copied it to new Summary tab.
2. I did vlookup per your example to "copy" Oct info to the Summary tab. This works great!

The problem I'm having now is, is there an easy way to find the missing item codes? The example I posted above only has a few items. But the actual data I'm working on can have hundreds of rows, and I'm trying to figure out an easier way to find the missing items. Any idea how I can do this?

Ah, I got it. Beautiful. Thanks humdingaling!