where Spatial Joins are based on proximity a join based on a matching attribute is simple. For example Transformers and Consumers. Using Transformers as the "base" feature and Consumers as the feature being joined to the transformers. A basic spatial join will leave you with all your transformers, and each transformer will have the nearest consumer joined to it. However, if the same consumer is 10 feet from one tran and 100 feed from the next tran, but the next nearest consumer is 500 feet from both, then the same consumer will be joined to both transformers. That's base ArcMap functionality, but what I need is the consumer that's 10 foot from a transformer to be joined to that transformer, then it can no longer be joined to any transformer, and then we keep joining until all the transformers have a consumer joined (or we run out of consumers)
