On the Import patrons page there are notes on the right side of the screen. The fourth bullet displays incorrect information regarding the import of multiple patron type and value pairs in the patron_attributes field. If you are importing more than one patron_attribute pair then the entire comma-separated list of attribute types and value pairs must be surrounded by double quotes. I am not sure if this applies to the "second syntax" as mentioned in the last sentence in the bullet. Instead of STARTDATE:January 1 2010,TRACK:Day it should be "STARTDATE:January 1 2010,TRACK:Day" I don't know if this is a bug or a template change and I don't know about the second example given on that page yet. "STARTDATE:January 1, 2010","TRACK:Day"
This does not appear anymore on the import patrons page.