Good Evening Joan, 

Thank you for contacting the U of M Extension Service. 

From viewing your photos, it appears the peppers on the plant on the left are brown and fuzzy. Their shape is not like a pepper. I have done some research and cannot find any related diseases or pests. I would cut off the strange fruit and hope the plant will produce good fruit in the future. 

Here is a link to the plant disease clinic: https://pdc.umn.edu/

You could submit a sample to the plant disease clinic for an accurate diagnosis. 

Also the fruit in the photo on the right. The most similar problem I can find is catface on tomatoes: https://extension.umn.edu/plant-diseases/tomato-disorders#how-to-manage-catfacing-3107962

Did you use a fish fertilizer or decomposing fish on the plants?  Is there any difference in soil or mulch or location compared to the "good" plant? 

Here is another link about growing peppers: https://extension.umn.edu/vegetables/growing-peppers

Good Luck!