Perhaps the ambiguity is clarified in Declarador vs. Gubatan and Bansales.

Where the “lacuna” there? as to fill in the void as to which is which?

1. Yes. Art. 63 of the Revised Penal Code deals with the application of indivisible penalties. Paragraph 1 thereof states that when the penalty prescribed is single indivisible penalty, it shall be applied regardless of any aggravating or mitigating circumstance that may have attended the commission of the deed. Particularly, with respect to the mitigating circumstance, the article should be understood to refer only to ordinary mitigating circumstances, and not to privileged one. Since ordinary mitigating circumstances tend to affect the period of the penalty only, it does not have a bearing in the application of the penalty when the penalty is indivisible or has no period.

It is however different in the case of privileged mitigating, as in the case of minority, which has the effect of lowering the penalty by degree/s. In such case, instead of imposing the indivisible penalty prescribed by law, the penalty next (or two) lower in degrees shall be imposed.

Hence, Art. 68 should be deemed as an exception to Art. 63, or more accurately, Art. 63 should be deemed inapplicable to Art. 68.

With respect to the discussion on RA 9344, (although I found it rather irrelevant since it does not appear to be required by the problem:)), I have the following observations:

RA 9344 modifies Art. 68 in the following manner:
(a) Subparagraph (1) is modified and should be read as “under 18 but over 15″ instead of “under 15 but over 9″;
(b) Subparagraph (2) is rendered useless. (Note: Not the other way around.)

2. The case in point is Declarador vs. Gubatan and Bansales (cited above).

Opinion lang po.. hehe
By the way, nice post bai Joselito Basilio.. keep posting po!
More power to you and to this site!!