"chia" vs "sia"?

[Mark Yong]

I have heard the Hokkien pronunciation for the word 斜 (xie2 in Mandarin, meaning "slanted") as both "chiá" and "siá" in Penang (with "chiá" being slightly more common. I suppose both are correct, but how does one classify the two different pronunciations by sub-dialect? Or are they wendu/baidu?

On the same note, the word 謝 is pronounced "ciă" as a surname, but as "siă" when used as "kām siă" 感謝 (thank you).

[hong]

chia5 is baidu sia5 is wendu.We should use baidu in this kind of adjective.modern nouns should be in wen du like hard disk ,software.taiwanese say hard/software in pc as baidu compare to wendu of china.
謝 sia7 is wen,cia7 is bai.I am not sure minnan should this surname as cia or sia because some is different like 林use wen-lim but not bai-na