what happens when multiple users change the same products at the same time?

Die deutsche Fassung finden Sie hier.

Example: A product is edited by two different users at the same time. User 1 and User 2 edit two different attributes of the same product.

User1 edits attribute A for the product and his product status is yellow
User2 edits attribute B at the same time for the same product, his product status is also yellow
User1 clicks on save products. cobby transmits the SKU, the ID and the changed value of the attribute A to Magento.
User1's product status turns from yellow to green, the contents of his Excel workbook match with the data in Magento.
User2 does not receive a red product status for this product, since his product status was yellow already.

User2 clicks on save products. cobby transmits the SKU, the ID and the changed value of the attribute B to Magento.
User2 receives a red status, his workbook was missing the changes from User1.
User1 receives a red status, his workbook was missing the changes from User2.

Both users click on load products to resolve the red status. Both receive a green product status.
Clicking load products only updated currently missing / currently red statuses in their respective workbooks.

Neither of them did interfere with each others work.

Only changed attribute values are transfered by cobby for the affected SKUs.
Since cobby release 1.34 SKUs that already have a yellow status don't turn red when a change is transmitted from Magento.

Is only the edited attribute changed in each case, or does the product status turn red for the user that saves last and is the change user2 has done not saved at all?

Both changes are processed successfully and both are saved.

The only scenario where this case can cause trouble is when you save the workbook locally, while yellow statuses are present, and then rebuild the cobby index before clicking on save products from the locally saved workbook. In this case internal IDs and product-versions will have changed due to the index rebuild and the data in your locally saved workbook differs from the data in cobby and Magento.