Return it for an accent color instead. You'll never get it to match.

Get some cats. ;-)

Seriously, it's very hard to "age" leather after it's been installed on a piece without actually destroying the finish on it. If it were still an unfinished hide, you could beat it up a little more effectively. It also depends on how it was dyed - if the color doesn't go all the way through, all you'll manage is to make a bunch of white scratches on it.

If you're absolutely set on trying, and are not going to send them back no matter what: you could try extremely fine sandpaper (c. 400 grit) plus your own fingernails to rough it up a little, gently. But in terms of lightening the color I don't think you're going to have any luck. You could try setting them in the bright sunlight outside for a while?

Thanks. I'm going to try the sunlight maybe when it's a bit warmer outside! It's not that bad, not really noticable in daylight, just incandescent light seems to bring out the difference. It's not an issue of wear, so I don't think beating it (!) will help. It's more a sheen/hue difference.

Is it lighter or darker? If it is darker you can't do much about it. If it is lighter you can use leather dye to darken it a little. Start testing the dye in an not so visible area. Maybe where it is wrapped underneath.