Two plugins doing one job.
WHERE IT HAPPENS
- Caching: two caching plugins conflict badly
- SEO: two SEO plugins produce duplicate meta tags
- Security: overlapping firewalls block legitimate traffic
- Image optimisation: two plugins processing the same images
- Forms: several form plugins, one actually used
WHY IT HAPPENS
A plugin installed, a better one found, the first never removed.
Or a theme bundling functionality a plugin also provides.
WHAT IT CAUSES
Conflicts and unpredictable behaviour Duplicate output Wasted resources Confusion about which setting applies
HOW TO FIND IT
List every plugin and what it does.
Group by function. Anything with two entries needs resolving.
WHAT TO DO
Choose one, configure it properly, remove the other.
Back up first.
THE CACHING CASE
Particularly important. Two caching plugins produce genuinely strange behaviour.
Only ever run one.
