Short answer: merge duplicate contacts from Google, Samsung, and SIM accounts as a source-overlap review task, not as blind deletion. The same person can appear more than once because each account source contributes a slightly different record.
This problem is common because the duplicates are not always true copies. One entry might come from Google, one from Samsung, and one from the SIM card. The merge needs to protect the useful fields that each source still contributes.
Why these duplicates happen
Google, Samsung, and SIM accounts each sync or store their own contact copy.
Imports and device changes preserve old records instead of replacing them cleanly.
Different sources may hold overlapping but not identical phone numbers, emails, or notes.
How to merge them safely
Review overlapping names as source-specific merge candidates, not instant deletions.
Keep the most complete record as the likely base.
Make sure useful fields from the other account sources are not lost during the merge.
Leave unclear edge cases for a slower second pass.
When this is part of a broader organization cleanup
If duplicate contacts are only one part of a larger Android cleanup problem, the best next step is not staying inside the contact list forever. It is folding contact cleanup into the wider organization route once the obvious merges are done.
If you want the feature route next, open duplicate contacts. If you want the broader organization path, continue to organize contacts and calendar.
The safe way to merge contacts from Google, Samsung, and SIM is to merge information, not just rows.