#2 -- two similar-looking guitars from the same brand will likely never have identical numbers. Nowadays, most s/n use half their digits to indicate approximate manufacture date, which will take a century or more to repeat. It's possible that two entirely different models (but same brand) from different factories would have the same number, but one or both would have a prefix (one or two letters) to differentiate.
#1, part 1 -- there's never been anything particularly wrong with non-US guitars. Arai (Aria) in the 1950s found that acoustic guitars built in Japan, even if top-quality, would split & warp after a few months in the United States. Arai learned how to properly cure tonewood for long-term stability, a lesson quickly picked up by Japanese manufacturers in general. Converseley, there's plenty of low-end mass-production USA garbage (Harmony, Kay, Valco, etc.).
#1, part 2 -- new factories have "teething pains" as they work the "bugs" out of supply, construction, assembly, finish, & shipping. I consider Mexico Fenders to be as good as their USA twins, but early MIM Fenders are often worse than current $300 Squiers. Early Korea guitars & early Red China guitars, much the same. The sole exception might be Indonesia, & that mostly because MII guitars are almost certainly Cort, who opened a huge factory there in the '90s.
Korea Washburn electrics ~1996-2010 are generally great guitars, & their market value seems to creep up daily.
Overall, an early-run guitar might beat the jinx & still be an incredible instrument, so it's not damning... but anyone who buys blind (without actually playing the guitar first) & pays "collectible" prices is foolish.
