Double Flush

Are double flushing toilets indicative of a deficiency or are some brands designed that way?

Typically, a deficiency:

http://www.redbeacon.com/hg/why-does-my-toilet-flush-twice/

http://www.bobvila.com/posts/50639-please-help-toilet-flush-twice-everytime-i-flush?page=1#.VRtSIkt2TFE

But, when switching to the 1.6 gallon flush toilets in the early 90s there were some problems:

Thank you for the info, I do appreciate it.