Hello guys, I merged your topics since you both posted about similar issues.
I'll answer the simple questions first. You can not have multiple inventories or tradelists right now, and this feature is not planned to be implemented soon. Having multiple accounts is against the rules because of possible trading scamming, but if the reason for having multiple accounts is clearly stated in the profile, we will not ban anyone.
The longer answer is that we have promised (a long time ago ) a feature that would allow users to tag cards in their inventory / tradelist / wishlist with custom tags, and then filter the set by these tags.
We've actually designed the widget and the functionality now, and I'm looking forward to implementing the first version of that sometime in the following weeks.
That feature would allow Paul for example to tag (while inserting them) cards as "Location: MTGO", and then by using a simple filter to see only those in the inventory. It will still not be a very strict separation between those cards. They will still behave the same when added to trades, or used in trading opportunities listings etc. So if you guys do want a very STRICT separation, multiple accounts is the only way.
If the labeling solution is sufficient, then keep an eye out on the annoucements forum in march