Many-to-Many Relationships

So, here we are. staring down two tables in the field of insight battle. It's a standard (if highly simplified) "Budget vs Actuals" situation. We are total n00bs, and we see some fields that look similar, and we think. "sweet, let's relate those two bad boys!" Alas: The relationship cannot be created because each column contains duplicate values. Select at least one column that contains only unique values.