Method for attributing opportunities to an advertising campaign

Context 

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

Attribution of Opportunities to a Channel 

Facebook, Google & LinkedIn

To attribute opportunities to Facebook, Google and LinkedIn we use a 12 month lookback period. The requirements for attributing an opportunity to a Google, LinkedIn or Facebook campaign are: 

1. An account or contact is launched to Google, LinkedIn or Facebook from Rev.Up
2. The account or account associated with the contact must have also had a web visit and you must have configured custom parameters on your ads. Without this, we are not able to make an association between the Rev.Up campaign and the campaign in the advertising platform. 
3. An account must have an opportunity created within the last 12 months. 

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.