As per Truecaller's privacy policy, the below points can be noted for data that can be processed and shared as logs on Call Me Back for users who have more than one sim on their device:
The data of users who have more than one active sim on Truecaller app versions 14.25 and below cannot be shared. As a result, these logs will reflect as "Phone number not available".
When such users update to the latest version of the Truecaller app that allows them to manage their data sharing preferences, Truecaller will be able to collect and share the exact number of the user in line with the latest privacy policy.
The data of users who only have one active sim which is registered on Truecaller will be available without any impact across all versions of the app.