Threshold is pronounced like "thresh-hold" [as noted in this question](https://english.stackexchange.com/questions/161655/why-is-threshold-pronounced-thresh-hold), however, what is interesting is that there is only one _h_ in the word, and it serves two phonetic roles (being part of _sh_ and as a regular _h_). This is different from words such as withhold, which have a separate h for the _th_ and _h_ sounds. While I suspect that this is due to a mixture of etymology (as threshold comes from the middle English "thresshold" according to Merriam-Webster) and pronunciation (the _h_ sound in threshold is unstressed), I am not sure. 

My question is: are there any similar words in English (i.e. words that have one letter serve as two phonemes)?