A man with one watch knows exactly what time it is. A man with two can never really be sure.
Get a set of check weights.
As far as scales, I've got an RCBS 505 and it is accurate and repeatable.
Chubbs
I've used a RCBS 1010 for over 30 years and it is still as accurate as when it was new. But, get a set of check weights, a little variation in the level of the bench or shelf you have it on can change the reading on any scale.
If you’re working with Lee Powder Scale you’d most likely have one of their “yellow dippers”don’t you? Just look at LEE's volume/weight chart that comes with their reloading dies or reloading manuals for a given size dipper and powder you’re working with, set the scale to that given weight, dip the dipper into your powder and pour it onto your scale. If your scale shows what you were looking at in the chart...you’re golden.