I have the following sentence
the user specifies some anchors by selecting some elements of the page.
Is it an alternative to avoid repeating "some"?
You can always avoid repetition by searching synonyms. If you're talking about a small quantity here, synonyms for some are a few, several,... Just be careful that introducing the synonym does not alter the meaning of the sentence.
In your case you could say, for example:
- The user specifies several anchors by selecting some elements of the page.
- The user specifies some anchors by selecting a few elements of the page.