I've read in some places that you should NEVER use more than one coat of stain on hardwood floors, while other places state that you can use multiple coats to achieve the color you want. So I'm confused - which is correct?

The reason I ask is that the floor company we are using stated that they didn't think the results of using the initial coat of stain was very good (we didn't like the look of the ebony Minwax sample provided due to not being dark enough, so used another brand). Once applied, it still wasn't as dark as I'd hoped, but I still thought it was better than the Minwax. Anyway, the guy recommended using the Mixwax over the other stain, so we went with that. The color is now what we want, however, once they started putting the poly on, there were issues. We can live with some of the issues (such as some areas being slightly lighter - we're not expecting perfection, especially with dark floors), but there are other issues that appear unrelated to the stain. For example, after approx. the third coat of poly (Bona Traffic), we noticed huge scratches along the floor in one room, then noticed some in another. The company is acting as if we must have done it (yes, I wanted to screw up my new floor, so I went and scraped something across the entire room!), and still insist it goes back to the original stain before they used the Minwax.

However, we've now realized that the scratch in one room corresponds to a fairly deep scratch that was there BEFORE they sanded (this room had existing wood that was being refinished), but for some reason, it wasn't noticeable until the final coat of poly. Is it possible that this is actually more related to the initial floor preparation - such as not getting the original scratches completely sanded out, but they just weren't noticeable until the end? We're extremely frustrated since it's been almost 2 weeks of dealing with this now and the company continues to act as if it's either 1) the non-Minwax stain or 2) we did something to cause the scratches. Too bad we don't have a photo of the scratch on the floor BEFORE starting all this, since then it would be very apparent that it's the SAME scratch, at least in one room - I think that's the issue in the other as well (the other room had new unfinished wood, so any scratches weren't so apparent before sanding and finishing). Thanks for any input or insight into this!