Only One Day of Passover?

Looking at B'ha-alotkha we find an observance from the Torah that might drive many of us to plan long trips during a certain Spring holiday.  The Torah speaks of the situation when one cannot observe Passover due to being ritually impure from contact with a dead body, or if one is on a 'long trip.'  This second Passover existed so that one could remain tied to the community's holiday of Jewish identity.  Ironically, the Haftara (reading from the prophets) for this Torah portion is shared with the haftara for the Shabbat during Hanukkah, another holiday that was also...a 'do-over.' Numbers 9 Zechariah 4