Department of Mathematics and Statistics Mohahanlal sukhadia University ,Udaipur -313.001 (India) 

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Graph labellings are studied mostly using the conventional definitions and without the use of computer. This paper studies the effect of allowing exactly one vertex label to be repeated in the conventional vertex labelling methods namely Harmonious, Sequential and Graceful for certain graphs and studies its effects with the help of a specialized computer software. This software can check the existence of any major kind of graph labelling scheme namely Harmonious, Felicitous, Sequential, Graceful, Magic and Antimagic for any kind of graph. It has been found that certain cases which otherwise are known to show no labellings with conventional definitions, produced several labellings on repetition of a vertex label using the computer. The labellings produced are also faster and several in number on the computer when a vertex label is repeated. Moreover, repeating a vertex label can also have significance in the areas of applications where the repeated vertex label could represent some special entity which needs to be repeated. This opens up possibilities for studies to obtain more labellings and can be explored further.