Yeah, I wrote that comment pretty quickly without thinking too hard, try this:
*** settings ***
Library Collections
*** test cases ***
eval test
@{documents} Create List doc_.doc main doc_2.doc appendix doc_3.doc background
${i} = Set Variable 0
${d} = Set Variable 0
${count} Get length ${documents}
${count}= Evaluate ${count} / 2
FOR ${document} IN RANGE ${count}
${document_name} Get From List ${documents} ${i}
${i} = Evaluate ${i} + 1
${document_kind} Get From List ${documents} ${i}
${i} = Evaluate ${i} + 1
${d} = Evaluate ${d} + 1
Set Test Variable &{document${d}} documentname=${document_name} documentkind=${document_kind}
END