There is no issue, depending on your perspective. The NT samples are from normal tissue. The TP samples are from tumour tissue. It is well documented that biopsies taken from 'normal' / stromal tissue surrounding the primary tumour can resemble the tumour itself. This is where we enter the debate of when cancer begins. A geneticist may say that it begins in the very first cell that accumulates a point mutation in, e.g., an oncogene, but this still may occur many years before conventional diagnostic / screening methods can detect a palpable tumour.
The other possibility is that there is a sample mix-up, either in your code, the inner code of TCGAbiolinks, and / or at the TCGA source.