Fewer results when duplicating phrase in a query with OR

[Mónica Marrero]

Hi,

I am using Solr 7.7 in Cloud with the default query parser and similarity
algorithm. I get the following results with these queries:

q= "Wolfgang Amadeus Mozart": 8834 results.
q= "Wolfgang Amadeus Mozart" OR "Wolfgang Amadeus Mozart": 8831 results.

To my surprise, I get 3 fewer results with the second query, and I have
seen that those 3 documents contain the same words in a different order
("Mozart Wolfgang Amadeus").

In case it is relevant, the field used for the query is a textual field,
with regular normalization (see below):

<fieldType name="text_general" class="solr.TextField"
positionIncrementGap="100">
            <analyzer type="index">
                <tokenizer class="solr.WhitespaceTokenizerFactory" />
                <filter class="solr.WordDelimiterGraphFilterFactory"
splitOnNumerics="0"/>
                <filter class="solr.FlattenGraphFilterFactory"/>
                <filter class="solr.LowerCaseFilterFactory" />
                <filter class="solr.ASCIIFoldingFilterFactory"/>
            </analyzer>
            <analyzer type="query">
                <tokenizer class="solr.WhitespaceTokenizerFactory" />
                <filter class="solr.WordDelimiterGraphFilterFactory"
splitOnNumerics="0"/>
                <filter class="solr.LowerCaseFilterFactory" />
                <filter class="solr.ASCIIFoldingFilterFactory"/>
            </analyzer>
        </fieldType>


Does anybody know why this is happening?

Thanks in advance for your help.

Mónica

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