Detailed tests were ongoing and have now been concluded, and here are the numbers: The male in his 30's received a total of 678 mSv, and the gentleman in his 40's was exposed to 643 mSv. Radioactive Iodine and Cesium were the primary dose contributors.
Interestingly, the two employees "told the health and labor ministry that they don't remember whether they wore protective masks or not when a hydrogen explosion occurred at the No.1 reactor on March 12th".
So it seems like they weren't wearing masks, nor did they take any potassium iodide pills at the appropriate time.
Another male in his 50's is now suspected of being over the 250 mSv limit. Tests are in progress to determine his cumulative exposure.
Read the story at NHK here