If you have a compound mitre saw set the saw up to about 30 degrees in both settings and cut both pieces with the same setting. They will butt up perfectly together and the angled joint is stronger and less noticeable than a vertical one.

If you don't have a CMS then I'd just cut each board end to about 30 degrees, use one when cut, to scribe  a line on the other so both angles are identical.

Thanks for all the help!