When stacking a two tier fondant cake is it preferable to put a dowel rod in the middle of down both cakes? Some say they don't and feel safe! HELP

Sometimes I do and sometimes I don't. If the customer is picking it up and taking it themselves, I almost always do. Or if I'm delivering it anywhere too far, I will. Okay, now that I think about it, I probably dowel about 85% of the time. Better safe than sorry  I have used royal icing between the cakes when I've been in a pinch, but I don't know how trustworthy that method is.

I don't use a center dowel for two tiers, nor do I use RI.  In fact, I've never used a center dowel as I will only stack two tiers before traveling.  I assemble on-site.  Less stress while traveling for me.  I deliver all of my cakes, but I guess I would consider using a center dowel if someone was picking it up from me.

640cake,

if the tiers are fondant, do you use a little buttercream on top of bottom cake to hold the top tier?

Thank you!

 Yes, that is all I use to "glue" the tiers together, buttercream.  I use American Buttercream, if that helps or makes a difference.  And I always travel with a well chilled cake.