Will adding canonical affect traffic to the non canonical page?

[NanditaKraman]

We have three URLs that have the same content but all three are getting traffic.

[Dalerio-Consulting]

It depends on where the URLs are getting the traffic from. If the traffic is coming from clicks on the sites where the backlinks are located, then you're good.

If the traffic is coming from google searches, then it will depend on a case-to-case basis, but generally what will happen is that some of the rank of the pages with the canonical tag will be transferred to the page where the canonical tag is directed to, and while their google traffic might decrease, the traffic for the main page should increase.