A light spray of any pressure pack paint will help on the threads.
And not as permanent as Loctite.
If the mouths are close enough together, a small hole in each one and some tie wire will stop them
"Sometimes it's wiser to keep your mouth shut and appear ignorant, than to open it and remove all doubt."
"Such is life"...Ned Kelly, (Aust bushranger), just before he was hung by the neck.