How can I ensure that my reseller and I are not talking or going after the same customer. This has already happened on a few occasions where we get to a meeting and they tell us that they are already evaluating our product with our reseller, or vice-versa. I just can't seem to come up with a way where this can never happen again.
You need to have a way for resellers to register an opportunity with you. If the opportunity is not registered, it's fair game for direct. This should be built into your reseller agreement.
That depends on the kind of reseller you are talking about. If you have some sort of signed reseller agreement you might be able to restrict resellers by territory. That might, or might not, fix your problem.
In general, it is not possible to prevent reseller competition. Worse yet, if you are offering your reseller a substantial discount they might be able to undercut your own price!
You need to evaluate exactly why you need a reseller and what they can do for and against your business.
You have to get coordinated. Hopefully they will see this as a way to avoid over-lap and not an attempt by you to take any leads.
Offer to put together a list for them. Maybe you could offer to pay for some type of qualified list. Ask them to provide a list of their existing customers and prospects. Create a full list marking yours and their's. As a benefit to them, you could provide additional leads. Again, they won't go for this if they feel you are trying to take advantage.
If you are trying to rely more on resellers instead of your own direct sales. This could be a start to manage your reseller network as you grow and possibly create some territories. Providing qualified leads could be a way for you to 'follow-up' on resellers to motivate them to sell your product.