Such a thing as a Phal-Dendb Orchid?

Someone told me when i showed them a couple of pictures of my Orchid, which i identified as a Phal, that it was a Phal-Dend..combo.Could someone explain how does it arrive with such a identification? Does it mean that it was grafted? I bought this plant in Lowes a few years ago, and although i do not have the tag anymore, I believe it did say Phal on it.Well, after 4 years or more I finally got 2 spikes...one eventually shriveled but the other one is strong and starting to bloom with what looks like an all white flower. If i am not mistaken, when i bought it, it was naturally in bloom and that is what attracted me to it, though i have nil skill with Orchids. This is my first one. I believe the bloom that came as my first rebloom was a beautiful colored one...not 100% sure, since i gave up on it a long time ago. I just kept it cause the leaves were solid and attractive as a foliage plant. Can an orchid change colors of blooms due to culture change? BTW, does an Orchid that is in bloom get fertilized anyway?

Orchids are monocots, which do not graft. If the flower you are getting is now different from prior blooms, you might have two plants in the same pot.

Phalaenopsis grows as a single plant without any offsets or side shoots. It has strap-like leaves, each slightly folded along a center line. The leaves form one at a time and are alternating and opposing. That is, if the lowest leaf is to the right, the next leaf will be higher and to the left with the 3rd leaf even higher and to the right directly over the 1st leaf. There is no real stem to the plant except for a small "trunk" as new leaves form and old leaves die. The flower is roughly in the form of a disc with a small pouch or lip in the center.

I'm not really familiar with Dendrobium, but Sunset's Western Garden Book has a drawing of its flower. The flower resembles a Cymbidiam, with distinct petals and a large pouch.