My own view is in line with what Mark has offered in respect of my own experiences in buying and selling, but I thought it would be useful to see what it says on Ebay itself....and as always it is not 100% clear but my personal interpretation is that there is no indication that the additional item would be sent for no additional cost.

The link I looked at is this (and yes, there appear to be others and I have not checked them all)

https://www.ebay.com/help/buying/shipping-delivery/shipping-rates/saving-combined-shipping?id=4063&st=2&pos=1&query=Saving through combined shipping&intent=combined

The relevant parts IMO are "Many sellers will already have rules in place to combine shipping if you're buying multiple items, so all you have to do is add the items you want to your cart. You'll see the combined shipping total at checkout." and then "If the Shipping section of the listing doesn't specify shipping costs for additional items, you'll need to ask the seller before you pay. If the seller agrees to ship the items in one package, they'll send you a combined invoice detailing all the items, and the new cost of shipping."

This would indicate that the seller then has to confirm to the buyer what the revised shipping cost would be for more than one item.

I have myself purchased multiple items in the past and the discount (if that is the correct word to use here) was maybe not as much as I had hoped, and in other cases I have only been charged the shipping cost of one of the items to ship. My point is that I never assume one or the other.

Steve, if you have always had combined shipping that is at the price of a single item then I would respectfully suggest you have been fortunate certainly in your purchases and congrats on that, but I find that if it is not explicit in the description then best to ask just in case.

I have no axe to grind here - just trying to see both sides and note what Ebay itself says (albeit not very much for this specific case).

Happy chipping all

Jason