how did DPP manage to double the number of its seats in the legislature? I’m somewhat puzzled by this.
What’s the problem? They did poorly in 2008. With up to 46% of voters supporting Tsai, don’t you think that would translate into winning more seats in the legislative? 
And they didn’t double the number of seats they won last time.
What’s the result?
The KMT have something like 64 seats and DPP 40 seats. TSU and PFP have a handful each.
With Ma’s win by a few % and DPP’s gain in the LY but failure to clinch a majority, it means the KMT stays in power, but it also serves as a warning shot to the KMT not to take things too far to the deep blue end of spectrum.
DPP coming from a low ebb, too. They got 27 seats in 2008. They also made progress in the percent of votes for the Presidency.