I store all my flavors in an old humidor and have never experienced flavor transfer from another juice nearby, though have heard this too. If the juice is strong enough to smell in a sealed bottle (Virgin Vapor's red hot cinnamon is like this) -- just store it separately.
If you're taking the cap off during steeping (I personally never do -- I instead 'breathe' the bottles once every day or 2 along with sit time) -- I imagine the possibility of flavor transfer is much more likely.
If you're taking the cap off during steeping (I personally never do -- I instead 'breathe' the bottles once every day or 2 along with sit time) -- I imagine the possibility of flavor transfer is much more likely.