Using a Jasper Report with a Textfield in Markup HTML *and* using e.g. "<ol>T E ST I N G</ol><br/>" as the Textfields expression causes a two Sided PDF Report to be created.
Using e.g. "<ol>1</ol><!-- --><br/>" as an expression works as desired. The same happens using <ul>.
Attached is a Sample report
Version was 6.20.0 (does not exist in version chooser)