Yes, you can. First, open the base texture, the one that will form each corner. Then upsize the canvas (not the image, the canvas) to be exactly twice the height and twice the width of the original image. Do not "center" the image on the canvas, be sure it stays in one of the corners. DO NOT RESIZE THE LAYER TO FIT THE CANVAS. Now select the layer the base is on and duplicate it. Use the Flip (yes, Flip, since this is the tool that mirrors the image) either horizontally or vertically. Then use the Align tool to place this second layer in the corresponding corner of the canvas. Repeat until you have all four corners. Now, in the Layers panel, right click one of the layers (no matter which) and select "Combine visible layers", "Expanded as necessay". Now you can resize the whole image to fit the proportions and size your final texture needs to be. Cheers!