You should only have one set of kernel module extensions in onboot.lst:
piCore-8.x armv6 - *-4.4.39-piCore+.tcz
piCore-8.x armv7 - *-4.4.39-piCore_v7+.tcz
piCore-9.x armv6 - *-4.9.22-piCore.tcz
piCore-9.x armv7 - *-4.9.22-piCore-v7.tcz
..so, for example, you should only have one of the following in onboot.list
alsa-modules-4.4.19-piCore_v7+.tcz
alsa-modules-4.4.19-piCore+.tcz
alsa-modules-4.4.39-piCore_v7+.tcz
alsa-modules-4.4.39-piCore+.tcz
So far, only the in-kernel modules have been compiled for piCore-10 and the ones not inlcuded in piCore-10.0beta5a.zip have not been made into extensions.
This means that, unless you make your own extensions from 4.14.33-piCore-v7_modules.tar.xz, you will need to wait for the final release of piCore-10.