Suggestions On Soaking Stamps

I have this collection of passport stamps from Zaire but they are all stuck to one another. Passport stamps in my experience tend to have stronger gum used to affix them and it took a long soak in hot water to get these off the pages, but not from each other. I would like to try to separate them and was wondering what suggestions everyone had. These stamps are uncommon but I do have a pair of torn duplicates I am willing to test ideas on.

I would leave them be or the embossed image will be lost...