I'm also not sure if I'm oversimplifying your question (because I'd give the same answer as tfguy44), but maybe this is what you're after. Since the quads are both from the same image you can use a beginShape(QUADS); with one texture(img); and then use different get-set parameters for each quad. I've placed these in a textureQuad function that gets a square from the source image and then draws (sets) the textured quad. So for clarity, you can make as many textures / textured quads from one source image as you want. Let us know if this is what mean. Or if not, please give some additional info.

Code Example

1. import processing.opengl.*;
2. PImage img;
3.  
4. PVector getA = new PVector(300, 300);
5. PVector setA = new PVector(450, 350);
6. PVector getB = new PVector(400, 400);
7. PVector setB = new PVector();
8. int getAsize = 300;
9. int setAsize = 200;
10. int getBsize = 200;
11. int setBsize = 150;
12.  
13. void setup() {
14.   img = loadImage("http://www.backyarddesignslighting.com/wp-content/uploads/2011/08/Landscape-2.jpg");
15.   size(img.width, img.height, OPENGL);
16.   noStroke();
17. }
18.  
19. void draw() {
20.   background(img);
21.   setB.set(mouseX, mouseY, 0);
22.   beginShape(QUADS);
23.   texture(img);
24.   textureQuad(getA, getAsize, setA, setAsize);
25.   textureQuad(getB, getBsize, setB, setBsize);
26.   // etc.
    
27.   endShape();
28. }
29.  
30. void textureQuad(PVector get, int getSize, PVector set, int setSize) {
31.   vertex(set.x-setSize, set.y-setSize, get.x-getSize, get.y-getSize);
32.   vertex(set.x+setSize, set.y-setSize, get.x+getSize, get.y-getSize);
33.   vertex(set.x+setSize, set.y+setSize, get.x+getSize, get.y+getSize);
34.   vertex(set.x-setSize, set.y+setSize, get.x-getSize, get.y+getSize);
35. }