I usually use the save & duplicate option and I've noticed that whenever I do that it always uses the URL from the first product I created and then I will create other products by changing the product name and maybe another option and every URL will be the exact same with a different number at the end and I don't know how to fix this or if this is a known issue with Magento 2.1.6
Example:
I started by creating this product:
https://www.ooples.com/black-butler-ciel-pink-ballgown-5-plush-keychain.html
Here are the next 2 products I created using save & duplicate:
https://www.ooples.com/black-butler-ciel-pink-ballgown-5-plush-keychain-1.html https://www.ooples.com/catalog/product/view/id/54914/s/black-butler-ciel-pink-ballgown-5-plush-keychain-2/
Not only are both URLs completely wrong but even the format for the second one is completely different from the others and all of my URLs are set to be like the first one. I don't change any settings other than product name and the product photo and maybe a category here or there.