My very simple FetchXml query just needs three attributes from the contact entity:
If I run this in xrmToolbox's FetchXml tester, the results are:
">
Abraham McCormick
10
cv11 6ur
{25A17064-1AE7-E611-80F4-E0071B661F01}
However, running the exact same query through RetrieveMultiple, I get:

Where did address1_composite come from? What might I be doing wrong?