(Cleric 1, Str 14) equipping a quarterstaff as a Double Weapon and export to PDF as Standard sheet, I see 3 blocks:
1st: "Quarterstaff" total attack bonus -6;-6, damage 1d6+2/+1
2nd: "Quarterstaff (Head 1 only)
1H-P has N/A to hit (also 1H-O and 2W-P(OH) - fair enough, a double weapon isn't off-hand)
3rd: "Quarterstaff (Head 2 only)
single entry, attack +2, damage 1D6+3 – the values for use as a 2H weapon only.
Also: it's too easy to equip a Quarterstaff as "Both hands" not "double weapon" - irritating, 'cos then you think there's a different bug as only 2H shown
windows 7-64, java 6, pathfinder core book