I don´t know why others are not the same. Probably less kilometers? Not hotter conditions? Image light effect of picture? Clean/brush pipes?I only know all boxer I have seen have the same blue-purple-orange colors if they are chrome plated finished. If pipes are not chrome plated (only steel) they will get worse a bit rusted and dirty etc.
I only get worried about colour if both are not the same. If each cylinder is different colour probably is not working properly.
Here you can see. From purple (hottest part), blue and orange.
