Fix context duplication in pdf output

copienator/utils.py

@@ -70,7 +70,7 @@ def pdf_images_of_contexts(root_dir, label, all_labels):
 
     pertinent_contexts = []
 
-    for filename in os.listdir(text2_dir):
+    for filename in sorted(os.listdir(text2_dir)):
         if filename.startswith("CTXT ") and filename.endswith(".pdf"):
             # Extract "first_label -> last_label" from "CTXT first_label -> last_label.pdf"
             core = filename[5:-4]