I cannot emphasize more the importance of setting the correct layer breakpoint for dual-layer DVDs, the so-called DVD-9.

Most software, including the famous ones such as DVD Studio Pro and Encore, sometimes set the layer breakpoint at the wrong place.  But your question is: It works though.  Yes, it may work on your DVD player but may not work on other players.  There is a very funny phenomenon in the DVD player market; i.e. the cheaper the DVD player, the more compatible it is.  Why?  Because cheap DVD players are created to play the cheap bootleg discs and if the requirement is too tight they may fail to play.  On the other hand, brand name players such as Pioneer, Sony, Philips, etc. confirm the DVD forum standard so they will reject bad discs, including dual-layer discs with a bad breakpoint.

When you have a dual-layer order please make sure to hire a company that knows how to set the correct layer breakpoint.  If the layer breakpoint is set incorrectly a knowledgeable replicator such as New Cyberian should be able to fix it without the need for re-authoring.