RTP Campaigns in Google Analytics - Impression metrics differ

We have integrated webpersonalisation campaigns within event reporting in Google Analytics to see impressions and clicks on dialog banners in  GA reports. I now recognised that click event data is exactly the same as reported within the campaign webpersonalisation section of Marketo, while impression events are 3-4 times higher in Google Analytics compared to Marketo Webpersonalisation Analytics.

Is there anyone having the same issue? Could you come up with a reason why this data is so different in those two reports?

Thanks!

Karoline