text: Comment from WolfMan: "Copying any map data from proprietary commercial maps is never a valid practice -- unless permission is specifically given, which is actually common with government map data. (In the USA, the government actually turned over at least 3 different types of comprehensive maps to OSM.) However, using multiple other maps - along with other sources - to get an idea of prevailing usage of names is valid.
  
  Also, proprietary position/geometric data may be copyrighted, but street names cannot be copyrighted because they are necessarily public domain. No exceptions.
  
  Going with a very small sample, biased by your first impression, is not a good idea. We spoke with many locals in the area (businesses, taxis, etc. trying to get directions or answer questions) and they all were confused by the "r" and corrected us by omitting it. That is the definition of prevailing usage.
  
  I have also noticed that in Bangkok the side streets that are ostensibly named after the main streets (apparently part of the Thai system of naming streets) are usually spelled slightly differently, probably to make them distinct from the main roads. For example, main streets that start with "Ratcha" vs. side streets starting with "Raja" and main streets "Muang" vs. side streets "Mueang". That agrees with your photos of side street signs using that other spelling and confirms the main street being different."