Are the following two sentences identical?
It has given me real satisfaction and motivated me to perform my duties toward mankind.
It has given me real satisfaction and has motivated me to perform my duties toward mankind.
They're very close in meaning, but not identical. The use of the present perfect tense in
has given and
has motivated implies the action has taken place once or more in the past in a general sense, but there is no hint of termination.
The use of the simple past tense (or preterite) in just
motivated implies the action is completed.
This example might make the distinction more obvious:
It has been raining sporadically this month, but it rained heavily yesterday.
In other words, it might still rain some more this month, but yesterday's downpour is done.
Yes, those two are equivalent in meaning.
Often the second "has" will be inserted to add emphasis, particularly when speaking. Try saying (without breathing):
It has given me real satisfaction and motivated me to perform my duties.
And then try saying (with emphasis placed on the italicized word and pausing to breathe where indicated):
It has given me real satisfaction [pause] and has motivated me to perform my duties.
If you dropped the second "has" in the latter, it sounds like the speaker has dropped a word.
Also note that you want "towards mankind" not "toward mankind." And, "perform my duties toward mankind" isn't particularly idiomatic. Perhaps try "perform my duties for mankind" or just "serve mankind."