@vic
Hi,
The photo posted isn't a double-flowered Saponaria officinalis (or even Saponaria officinalis).
For comparison, these photos show the flower characteristics of Saponaria officinalis:
http://www.google.ca/search?q=...

It was wracking my brain over what it actually was, and finally went to the site the photo came from.... they call it Saponaria vaccaria. (Looks like either they moved the photo or it was posted to the wrong species here.)
The current name is Saponaria hispanica and the photo shows a white form.
Some info (note the ribbed calyx):
http://fieldguide.mt.gov/detai...
http://botany.cz/cs/vaccaria-h...

Could you please ask to have it moved to the correct species?
Thanks,
Lori

Thanks again for your diligence Lori and I will ask @zuzu to move it.

In the future, as you find images that don't belong to the plant, if you will scroll to the bottom you will have the option to "move this image to another plant" - after you submit it, one of the plant admin's will do it for you and you and I both will be notified.

Yes, I knew about that, and have used it many times, but when I have, I've sometimes been told I should instead "comment" on the photo, or post it to Plant ID.
Here's the latest advice:
The thread "Silene stellata, S. vulgaris or other?" in Plant ID forum

It's always best to open the matter up to discussion in the Plant Photos Forum, and in this case there's nothing else Lori could have done because we didn't have an entry for S. hispanica or S. vaccaria. I've created the S. hispanica entry, with a notation that S. vaccaria is a synonym, and I've moved the photo there.

Thank you, Vic. Thank you, Lori.

Turns out there was a good reason for the absence of those entries. S. vaccaria and S. hispanica are now synonyms of Vaccaria hispanica, so the photo has been moved again.

Thank you so much zuzu