Double containers for strong materials.

As a relative newbie I've learned the hard way about separating and storing strong materials. I've lost a few to cross contamination.

Most of my strong materials are only 4ml worth. What is the best way to store them? Get 10ml vials and double them up?

Anyone have a list of materials that should always be stored separately?

I see images of people's organs and would like to know which ones can be stored side by side vs the ones with a high chance of cross contamination. I wish the places I buy them would mention this as well. Trial and error can be expensive.

Thank you