Will the above routine be considered over training?
No, because it's impossible for a routine to be considered overtraining. Even a program as obviously impossible for mortals as "600 sets of 3 back squats at 95% 1RM, 7 days a week, with a marathon for cardio" isn't overtraining, because programs aren't overtraining, an individual trainee's response to a program is overtraining. And even then, it's not a pure program/trainee relationship, but the program/trainee/circumstances relationship. Work or relationship stress, or insomnia, or summer heat, or missing meals can all cause overtraining when normally someone would do fine on a program.
Some people run a marathon every day for a year and aren't overworked. Other people need couch-to-5k programs. That's okay. The question is whether you are doing well on this program. Did you add too much physical stress too fast or was this was a gradual increase over time? Do you feel okay with your training load right now? Are you eating well? Sleeping well? Do you feel sore, and if so, is it too much? Do you have trouble getting out of bed? These are the questions to ask yourself.
But I bet that two twenty-minute walks aren't too much to worry about, on top of a strength training program. Make sure you drink enough water.