For symmetric geometric patterns, yes the pattern will be matched across the seams if you select the option of having the pattern fabric on both sides.For abstract, floral, dots, ikat, pictorial and other types of patterns, the pattern will not be matched across the seams. Each side of the pillow cover will show different segments of the design.For striped patterns, the stripe color sequence will be matched across the seam only for cotton prints or woven fabrics without a directional nap. For striped velvet fabrics (or other fabrics with a directional nap), the pattern will be placed with the nap flowing in the same direction on both sides. Please note that this will mean the color stripe sequence will not be identical across the seams.  The three photos below provide further explanation.Photo 1 (above):  Velvet fabric with a color stripe sequence and directional nap (indicated by arrow)Photo 2 (above): The default placement is with the directional nap flowing the same way on both sides. Each side of the cover shows the color in the same sequence (A, B, C, D, E) from left to right. However, note that the color sequence cannot be matched across the seams.Photo 3 (above): The color stripe sequence can be matched across the seam only if the nap is reversed on one side. This will mean one side of the pillow cover will feel smooth, while the other side will feel rougher because the pile is in the opposing direction. On some velvets, this might mean the smooth side will look lighter in color, while the rougher side will look slightly darker. Additionally, notice that in order for the stripe colors to match across the seam, side one of the cover shows the color sequence A, B, C, D, E, while side 2 shows the reverse sequence E, D, C, B, A.On directional velvet stripe fabrics (for example, see the Marlow or Seurat designs), we follow the placement shown in Photo 2 by default, unless you explicitly instruct otherwise. If you have a preference, please make this clear at the time of purchase. Figures 2A, 2B, 3A and 3B below use the Seurat  design to further illustrate the ideas above: