Absolutely they can. There may have been fundamental issues that have now been corrected which has led to Feb being accepted. Jan will remain unaccepted.
You could go back and try to amend the Jan programme to get a revised version of that programme retrospectively accepted but it serves little purpose and you can make better use of your time/resources. The only issue then is you have a two month gap (assuming the Dec programme was accepted) in order to assess compensation events that occurred then which might now be a little bit more subjective.
You cant turn the clock back now, but much better would have been to revise the Jan programme within a day or two of it being rejected and then sit down with the Employer to explain the changes made and if there is anything else wrong, to get a revised version then still accepted in January.