99 Elantra strut problem odd can not figure out.

On a 99 hyundai elantra , I just put timing belt on and other belts. The car ran fine. No problems with anything elese. Went out this morining and both front struts have collapsed. There is no oil leaks or anything like that. Both front ones just went out at same time with no systems. Is there anything that would contribute to this or do I have to replace them both. Thanks Kevin