Why not? As long as you aren't having to sacrifice other necessary items in the kitchen, an extra oven isn't a problem. Many homes have an extra stove in the basement.

I would consider the range oven and a single wall oven with perhaps a microwave stacked above the oven.

Your realtor is not correct. As long as you have two ovens, one in the range and one on the wall, you will meet any requirement for double ovens. Get another realtor. This one is closed minded.

"The single wall oven would be better for broiling as it would be under a vent" I am not sure what you mean by this.... the double oven needs to be vented too so you need to add that cost and possible more electric or gas work to get it hooked up into your cost calculation, not just the additional cabinetry.

I would do it if I had a kitchen big enough to be divided into zones. I'd have the double ovens in the main part of the kitchen and the single in the baking zone. Or vice versa if you bake zillions of cookies all the time.

I wanted 3 ovens (holiday cooking) but I planned on my third oven being a microwave/convection oven. Are you planning on a microwave? Where is it going?
I would get a layout before purchasing more appliances. If you're planning on a microwave, a range and the microwave stacked with the single oven, as Homechef59 suggested, might fit your plan better.

I think it would depend on the size of the kitchen and what you are giving up in order to house the extra oven. How often would you use 3? I personally would have no need for an extra oven. I also don't know why a double oven would be better than a range plus single?

I have 3 ovens, 4 if you count the micro. We use them all, not all the time but glad we have them. We have a 36" BS RNB (gas oven), a 30" Wolf (e-convection) in the wall and a Wolf CSO above it. We have a large kitchen w/zones and works out great. Baking - double ovens, cooking - RNB, beverage - micro. As for resale, as long as it doesn't appear that the ovens reduce usable cabinet or counter space and are easy to access without infringing on other appliance or work space I think it's a plus. It's one of those things where there really isn't a 'need' however if they work unobtrusively and the looks compliment the kitchen most people would be happy with 'more' than they need and would use them all.

I actually have 3 ovens and, while I can't speak to resale value, they are useful for me and they all 3 get used 8-10 times a year so it was worth it for me.
I have double wall ovens and then a range with oven.

disagree with your realtor. a lot of people barely use one oven, much less three ovens.

i would get the range and use the single oven that you already have. keep in mind that range ovens are usually a good deal larger than wall ovens.

I would rather have the extra storage and use a range w/oven and the single wall oven - wouldn't that count as a double oven kitchen for resale? That's what I was planning to do with my kitchen if we replace the counters.

range_+single wall oven = double oven. Third oven should have microwave or speed capabilities.

I say NO to a third oven. Most people these days aren't cooking nearly as much as generations past, so two ovens are a luxury -- three is overkill. Holiday baking only happens once a year -- you design your kitchen for every day use.

Most importantly, when you add in that third oven, you're taking away storage space, which is more important than duplicate items.

I also really question that real estate agents advise. Sure double ovens can look blingy, but is someone who likes your house really going to balk just because it doesn't have double wall ovens? I somehow don't think so. If the kitchen looks good in other ways and they are still getting the two ovens they would have to want in that situation I just don't buy it. As someone said, a range oven is nice and big in most cases and I'd rather have one nice big oven and one slightly smaller one than two smaller ones.
Get the oven combo that makes sense to you.