I have stored my 100% silicone toys loosely in a drawer for a couple years. My large collection of Tantus, Vixen, Happy Valley and Fun Factory toys are all stored together.
Imagine a drawer full of toys stacked on top of each other with no baggies or any separation what-so-ever, they are all free to mingle and touch each other as they please. I have not had any issues. Zero! ...and I do not expect to.
Cured 100% silicone will not melt simply by coming into contact with other 100% silicone toys. The problems come from toys that are not true silicone or by using silicone lubes on silicone toys. Some silicone lubricants may have a reaction and bond to silicone toys, damaging the finish. This is why you should always spot test before using silicone lubes with silicone toys.