@hawhill: perhaps someday the k3flasher tool could be smarter, and prevent overwriting known ("named") partitions just because a source image file is "too big".
It should have an override flag to ALLOW flashing multiple partitions at once, but that should be an exception and not the default. IMHO...
Still, the tool is great as-is, but it COULD be a bit more "noob-friendly" (i.e. safer)...