Fix double-processing of instructions

src/insn.c

@@ -34,6 +34,7 @@ void insn_execute(cpu_t *cpu, uint32_t insn) {
         }
 
         secondary_insn_handler[op2](cpu, insn);
+        return;
     }
 
     if (op > TABLE_SIZE || primary_insn_handler[op] == NULL) {