They are two separate countries now, unless you think North/South Korea are the same, Russia/Ukraine, etc.
No, they are not. The US legally recognized Taiwan (fka Formosa) as Chinese territory in 1943 and 1945 and legally recognized the PRC as the sole legal government of China in 1979, following a similar recognition by the UN in 1971.
https://www.congress.gov/crs-product/IF12503
There are only 11 countries in the world that recognize Taiwan as a sovereign entity and the largest are Guatemala, Haiti, and Paraguay.
https://en.wikipedia.org/wiki/International_recognition_of_T...
Separate countries? All but ~10 countries on Earth including the US and all of Europe have what's come to be called the One China Policy. Taiwan is not recognized as an independent nation. It's really Schrodinger's nation, both independent and not at the same time and God forbid anybody opens the box and forces the issue.