All printed chumashim that I've seen list the following consecutive selections as the Ashkenazi hafatarot for Vayakhel and Pekudei:
- Vayakhel: Melachim I 7:40-50
- Pekudei: Melachim I 7:51-8:21
(And see this list on Hebrew Wikipedia which says the same.)
However, this (leap) year on Parshat Pekudei I witnessed an Ashkenazi synagogue in Israel read both of these haftarot consecutively i.e. the haftarah for Parshat Pekudei consisted of Melachim I 7:40-8:21.
I subsequently saw this page on Hebrew Wikipedia, which notes that such is the Ashkenazi practice in Israel (except for in a year with two shabbatot chanukah, when Melachim I 7:40-50 was already read as the haftarah for the second shabbat chanukah).
What is the history of and the reason for this practice? (Why) is it unique to communities in Israel?
Some (possibly helpful) background
In most non-leap years Vayakhel and Pekudei are joined and are read together with either Parshat Parah or Parshat HaChodesh. In a non-leap year when they are separate, Vayakhel coincides with Parshat Parah and Pekudei with Parshat HaChodesh.
Thus in a non-leap year the haftarot of neither Vayakhel nor Pekudei are read.
In a leap year, Vayakhel and Pekudei are read separately, but one of the two weeks always coincides with Parshat Shekalim.
Thus, in a leap year, one and only one of the haftarot of Vaykahel and Pekudei are read.
The printed Ashkenazi haftarah for Vayakhel is the same as that of the second shabbat chanukah.
The printed Ashkenazi haftarah for Pekudei consists of the same selection as that of the second day of Sukkot (in the Diaspora) with two extra verses at the beginning.