making src/distrib/i386/floppies, I get

/usr/lib/libc.a(yplib.o): In function `_yp_dobind':
yplib.o(.text+0x0): multiple definition of `_yp_dobind'
libhack.o(.text+0x1370): first defined here
/usr/bin/ld: Warning: size of symbol `_yp_dobind' changed from 10 to 1402 in yplib.o
/usr/lib/libc.a(yplib.o): In function `_yp_check':
yplib.o(.text+0x680): multiple definition of `_yp_check'
libhack.o(.text+0x14d8): first defined here

Yet this seems to have been touch on in src/distrib/utils/libhack:
# $NetBSD: Makefile.inc,v 1.9 1999/06/30 22:21:57 fvdl Exp $
# Include this fragment to build libhack.o
# It is .o and not .a to make sure these are the
# objects you get (and not the ones in libc.a)

A work-around seems to be to remove yplib.o from
src/distrib/i386/floppies/ramdisk/Makefile:75 HACKOBJS:=...

Cheers,

Patrick