Oh, how wrong genealogists are when they say this. I had a case recently which demonstrates why, if the records are available, one should always research for a digital copy of the original record.
An extract of the birth record of Michelino Nania was ordered from the civil record's office in Catanzaro. It provided the following information.
Name: Michelino Nania
Record Number: 9 in Part II of the 1889 birth registers
Born: 16 January 1889 in Catanzaro
Parents: Carlo Nania and Grazia Di Barbieri
Annotations: There were no annotations in the margin of the original record.
However, his original birth record told a different story. The search for Michelino Nania’s original birth record took a fascinating turn. Michelino was actually born out-of-wedlock and initially abandoned by his natural parents. At the time of his birth and abandonment, the civil official gave him the name Michelino Macretta. Later on, both parents recognized him and he would have then taken his father’s surname. However, the original birth record is not usually altered except for noting these changes in the margin or by attaching additional paperwork.
It is interesting that the civil official in Catanzaro actually noted that there were no annotations on the original record. Perhaps there were none on his copy. However, the copy in the provincial archives, which was microfilmed, did indeed have annotations, as well as an attached Act of Amendment. Two copies of these documents/registers are made. One copy stays in the town hall and the other goes to the District Court [Tribunale] for seventy-five years, at which time they are transferred to the provincial archives [Archivio di Stato] for preservation.
I have abstracted and translated the genealogically pertinent portions below. (Used with permission)
Birth Record of Michelino Macretta (later Nania)
[Act] Number 9
On 16 January 1889 at 9:06 a.m., in the town hall of Catanzaro, there appeared Severina Ingrami, age forty, the “aunt/caretaker of abandoned children”, and a resident of Catanzaro. She declared that the male child she was presenting was found on the “ruota” at 6 Nazionale Street, near the hospital, at 4:00 a.m. that same day. The child was “recently born, wrapped in cloth, and without signs on the body.” The parents of the child are declared to be unknown and he was then given the name Michelino Macretta by the civil record’s official.
Witnesses to the presentation of the child were: Sebastiano Trioso [?], age sixty-eight, and a cobbler as well as Giuseppe Ranieri, age seventy-five, and a cobbler. Both of the witnesses resided in Catanzaro. Neither the declarant, Saverina Ingrami, nor the witnesses were literate.
There are two annotations in the margin of his birth record. The first notation reads: “On 8 March 1891, before the notary Giuseppe Scalfari, this male child of Grazia Barbieri, daughter of the living Giuseppe Barbieri, was hereby recognized as her natural-born child. The record number of the notarial act may be 6/5 96 [it isn’t clear].”
The second annotation reads: “By act of the notary Gerardo Giordano, son of Fosseto [?], dated the first of February [illegible year], this male child of Carlo Nania, son of the deceased Raffaele Nania, was hereby recognized to be his natural-born child. The number of the notarial act is likely 13/3808.
The second page is the civil act of annotation, prepared by the civil record’s office on a generic amendment form, with the approval of the district court [Tribunale] indicated. The act number is 189. By act dated 20 March 1891 by the notary Giuseppe Scalfari a male child is hereby recognized by Grazia Barbieri, daughter of Giuseppe Barbieri, who is from the town of Fossato. This annotation was transcribed onto the birth act of Michelino Macretta in the register for the year 1889, number “S.P” [Secondo Parte – Second Part]. The District Court approved said annotation on 31 March “91” .
 A stone wheel built within a wall that rotates the child inside a building or walled enclosure. The mother would then ring a bell placed outside so that the arrival of the infant could be announced. These wheels were meant to encourage anonymous abandonment and to discourage infanticide.
 Sometimes a piece of jewelry, a torn picture of the Madonna, a lock of the mother’s hair, etc. was left with the child so that, if the mother ever wished to reclaim him, it would help in the identification of which child was hers. They took pains to described exactly what was left and how the child was dressed within the document. Michelino’s mother did not leave anything, likely indicative of the fact that she did not anticipate being able to reclaim him.
 This document is quite rare to find still attached to the original record.