It's not really multiples palettes, if the line begin with 0xFD the 2 next bytes (a word, little endian) are the index used in the image palette (65535 colors) for the color index 0 of the line palette (250+1 colors).
In original nng images I never saw 0xFD inside a line always at beginning.
And always a multiple of 251 for the index.
The palette index defined on a line is not applied on the next line.
Bookmarks