proporzionalità and gradualità are two different concepts.

The former means (roughly) that the penalty must be proportional to the seriousness/gravity of the offence.

The latter means that, in case of recidivism, a higher/harsher (type of) penalty should be applied than that strictly based on the proportionality criterion.

In other words, in case of recidivism a penalty progressively (or gradually) higher/harsher should be applied, going beyond the strict application of the principle of proportionality.

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Note added at 52 mins (2013-10-05 11:01:45 GMT)
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(you will find sufficient corroboration to my point in the document you cited)

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Note added at 53 mins (2013-10-05 11:02:58 GMT)
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https://www.google.it/#hl=it&q="graduality of the penalty"

https://www.google.it/#aq=f&aqi=g10&aql=&gs_rfai=&hl=it&q="p...

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Note added at 3 hrs (2013-10-05 13:17:13 GMT)
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The word "principle", by nature, is usually followed by an abstract noun (e.g. "principle of proportionality") and less frequently by a circumlocution.
The "principio di gradualità della sanzione" being an Italian expression, I personally agree with the translation found in EUR-LEX which I cited right above, respectively:

"...excessive interpretation of Article 24(2) of Regulation No 4253/88, by ignoring the criterion of 'GRADUALITY OF THE PENALTY'.

and

"...fully consistent with the requirements of individualisation and PROGRESSIVENESS OF THE PENALTY"

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Note added at 5 hrs (2013-10-05 16:06:30 GMT)
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this is the second quotation in full:

"It does not seem to me to be fully consistent with the requirements of individualisation and progressiveness of the ‘penalty’ – two principles of cardinal importance in any punitive system, both in the criminal and the administrative spheres"

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Note added at 5 hrs (2013-10-05 16:07:39 GMT)
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and this is the direct link to it:

http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:...