Technically, single ropes are designed for individual use. Therefore, the diameter of single ropes is typically larger, ranging from 9.5mm to 11mm. Compared to other ropes, single ropes also tend to be heavier. On the flip side, twin ropes are designed to be used in pairs and have a smaller diameter.
If you use two single ropes as a twin rope, it will most likely become bulky and difficult to handle. However, there are a few single rope models that are certified to use as double ropes. Unless your single rope has this certification, we do not recommend you to use them as twin ropes.