Method for attributing opportunities to an email campaign

Context 

This article describes the D&B out of the box attribution model. This model is not currently configurable. 

Attribution of opportunities to an email channel 

Eloqua, Pardot 

To attribute opportunities to Eloqua and Pardot we again use a 12 month lookback period. The requirements for attributing an opportunity to a Pardot or Eloqua campaign are: 

1. An contact is launched to Pardot or Eloqua from Rev.Up
2. The contact must have engaged with your marketing content and this engagement was imported back into Rev.Up. 
3. The contact must have an opportunity associated with it that was created within the 12 months of being part of the Rev.Up campaign. 

If D&B is using a 12 month look back period to attribute opportunities to a campaign, does this mean that my opportunities can be attributed to multiple Rev.Up campaigns? 

To avoid a single opportunity being attribute to multiple campaigns, we use the last touch method to assign an opportunity to a single campaign.