If you want to compare strings using fuzzy logic, you either can use the step “Fuzzy match” or calculate the similarity within the “Calculator” step.
To comparing person names I found the “JaroWinkler similitude” algorithm with a score > 0.75 providing acceptable results:
Note: In this example “Grams, C. M” is obviously similar to “Grams, Christian Michael Warnfried”. With the Levenshtein distance, this similarity would not have been found.
In order to filter out false positives, you can run additionally the similarity check also on just the last name only.