Issue
Does Marketo re-use or recycle old deleted lead IDs?
Root Cause
After a lead is fully deleted, it would be very rare for the lead ID to be re-used. The vast majority of the time lead IDs are unique and not re-used.
If you have an external database or reporting system that relies on a unique lead ID, the best practice would be to ensure these systems are up-to-date on all lead deletions.
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