@Voice did not allow to use same group name (RegEx) for Edit Speech

Maybe this is because @Voice uses DEELX internally to process all substitutions (because it's written in C++, faster), but for checking syntax I use Android Java RegEx implementation (because DEELX does not give me the precise error messages and locations). So far for many years it worked OK, you are the first to report a problem with this issue. Maybe I could suggest an alternative approach, but would need to understand first exactly what you want to do - what text you want to match and how do you want to replace it.

I see. It really is a tough nut to crack. The TTS voice software that says handles Thai language should to this splitting correctly, but apparently it fails... The only solution that comes to my mind would be to warn the user about the suspect syntax error, but let you click something and still accept the RegEx, handle it to DEELX at the reading time and see what happens...
 
However, let's stop for a moment and ask: instead of entering many alternatives with | operator in one RegEx expressions, wouldn't the final result be the same, if you created a number of separate replacements, e.g.:
 
Replacement 1:
Pattern: (?<a>ทน)(?<b>ทาน)
Replace: ${a}·${b}·
 
Replacement 2:
Pattern: (?<a>เออ)(?<b>ออ)
Replace: ${a}·${b}·
 
etc....

I see. It really is a tough nut to crack. The TTS voice software that says handles Thai language should to this splitting correctly, but apparently it fails... The only solution that comes to my mind would be to warn the user about the suspect syntax error, but let you click something and still accept the RegEx, handle it to DEELX at the reading time and see what happens...

That is ok, thank you.
 

Or even give up on RegEx here to save time, battery and memory in processing all of this, and use replacement type "Case sensitive" (because it's the fastest), and write replacements like:
 
Replacement 1:
Pattern: ทนทาน
Replace: ทน·ทาน·
 
etc.

I used to do this replacement but it was inconvenient when I want to add a new replacement because I have to open old replacement to copy "·" first then back to insert new replacement to paste it.
 
with same group name RegEx capability, I just open the replacement, copy part of pattern ex."(?<a>ทน)(?<b>ทาน)|" then paste in front of pattern and only change Thai word to new one ex."(?<a>ก็)(?<b>อด)|"
 
I have just figured out what I really needed when I tried to explain you my reason. Actually I need a "Copy" or "Clone" or "Duplicate" button for Edit speech so I do not need to open old replacement to copy "·" then back to insert new replacement to paste it.

I now released @Voice version 17.2.0b to the beta test area on Google Play, where a long press on add or insert a new item to the Edit Speech list adds/inserts a copy of the currently highlighted item.