Wanting to install Manjaro in dual boot but one issue

I currently have Kubuntu 19.10 installed with the beta Kubuntu backports so I can have the latest Plasma desktop. What I want to do is install Manjaro 18.1.3 KDE on the backend of mu OS drive and dual boot with Kubuntu. I know under normal circumstances it would just be amatter of telling the Manjaro installer to use the free space and during Grub installation it would detect Kubuntu and add it to the Manjaro / Grub boot menu, but I have a odd issue. a couple of weeks the backports updated the Kubuntu kernel from 5.3.0.19 to 5.3.0.21 but whenever I would do a reboot the .21 would not boot. restart select Advanced Options select 5.3.0.19 and it would boot perfectly. Try as I might could never return the default kernel to the 5.3.0.19. A few days later was upgraded to 5.3.0.22 then 5.3.0.24 on the .24 when the system is rebooted it lands on the Advance Options instead of Start Kubuntu. Luckily I just hit enter twice and it goes right into loading ram disk and right into the desktop on the 5.3.0.24 kernel. I'm wonder with this be that way if it's going to cause any issues / confusion for the boot loader. thanks