CREATE (f:Foo)-[:FOO {a:1}]->(b:Bar {c:3})-[:BAR {b:2}]->(f) WITH id(b) as id
CALL apoc.refactor.collapseNode(id,'FOOBAR')
YIELD input, output RETURN *

Before we have this situation

And the result are

The property of the two relationship and the property of the node are joined in one relationship that has the properties a:1, b:2, name:Bar