In this Letter, we report that after oxidation in air and reduction in hydrogen the existing carbon nanotube arrays can be used as a substrate to grow another nanotube array. The two arrays are connected through a thin catalyst layer. Micro-Raman study of these two nanotube arrays shows that they have different characteristic spectra. Besides the small shift in the peak frequencies of the two kinds of arrays in Micro-Raman spectra, we have observed changes in the relative intensities of D, G and D' lines and proposed the mechanism of this phenomenon.