Just as you can’t copy commercially made VHS tapes to another VCR due to Macrovision anti-copy encoding, a similar applies to making copies to DVD. dvd recorders cannot bypass anti-copy signals on industrial VHS tapes or DVDs. If a dvd recorder detects anti-copy encoding it will not start the recording and display some sort of message possibly on display or on its LED front panel display that it detects the anti-copy code or that it is detecting an unusable signal.
Some practical advices:
Buy DVD versions for those films inside your VHS library which can be now accessible on DVD, specifically if they are films you like to watch on a regular basis. Since DVD has much better video and audio quality than VHS, as well as most DVDs having supplementary features (such as commentaries, deleted scenes, interviews, etc…), and as well as of DVD films getting fairly affordable (especially if they are already out for awhile), this would be a better option in conditions of time.
Keep in thoughts that it requires two hours to copy a two hour movie, since the recording is completed in real time using a DVD recorder, whether copying from a VHS tape or DVD. For example; it could take 100 hours to copy fifty films (if you are truly capable to do so) and money (you still must get fifty blank DVDs) invested on trying to make copies of old VHS films onto DVD.