Component id must be unique
Impact area
Scalability
Severity
High
Affected element
Apex Page
Rule ID
SF-0122
Impact
Your code can break if you use non-unique component ids and your page hierarchy changes.
Remediation
Make sure that you use ids which are unique at the whole page level.
Time to fix
30 min
References
See the Salesforce documentation article: Best Practices for Accessing Component IDs.