Are there any unknown "rules" against acquiring a second remote job?

[TripleThreat]

Background: I work from home, and I love my job. Due to this, I don't want to jeopardize my current job but would love to acquire a second "easy" remote job that I think I may be able to secure (in process). While it pays less than my current job, it would be a great way to just funnel this money into a bank account and let it sit.

Are there any precautions I should be taking, or any unknown rules I should know about when/if acquiring a second job? For example, does my HR or company get notified by any sort of outside source (such as when they send me my W-2) that another company is sending me a W-2?

What I have read online seems to be all over the place, and what I've generally come to the consensus of is that I can get a second job, and there shouldn't be any issue, just to make sure that I keep up the work for both jobs, if not, my "main" job which was already a given.....