Not true. My baptism as an 8 y.o. in a tiny Baptist church in Utah was sufficient. I was never required to be Baptized into the Catholic Church.
Another effect of baptism is the infusion of sanctifying grace and supernatural gifts and virtues. It is this sanctifying grace which renders men the adopted sons of God and confers the right to heavenly glory. The doctrine on this subject is found in the seventh chapter on justification in the sixth session of the Council of Trent. Many of the Fathers of the Church also enlarge upon this subject (as St. Cyprian, St. Jerome, Clement of Alexandria, and others), though not in the technical language of later ecclesiastical decrees. (4) Conferral of the Right to Special Graces Theologians likewise teach that baptism gives man the right to those special graces which are necessary for attaining the end for which the sacrament was instituted and for enabling him to fulfill the baptismal promises. ... In treating of the grace bestowed by baptism, we presume that the recipient of the sacrament puts no obstacle (obex) in the way of sacramental grace. In an infant, of course, this would be impossible, and as a consequence, the infant receives at once all the baptismal grace. It is otherwise in the case of an adult, for in such a one it is necessary that the requisite dispositions of the soul be present. The Council of Trent (Sess. VI, c. vii) states that each one receives grace according to his disposition and co-operation. We are not to confound an obstacle (obex) to the sacrament itself with an obstacle to the sacramental grace. In the first case, there is implied a defect in the matter or form, or a lack of the requisite intention on the part of minister or recipient, and then the sacrament would be simply null. But even if all these essential requisites for constituting the sacrament be present, there can still be an obstacle put in the way of the sacramental grace, inasmuch as an adult might receive baptism with improper motives or without real detestation for sin. In that case the person would indeed be validly baptized, but he would not participate in the sacramental grace. If, however, at a later time he made amends for the past, the obstacle would be removed and he would obtain the grace which he had failed to receive when the sacrament was conferred upon him. In such a case the sacrament is said to revive and there could be no question of rebaptism.(3) Infusion of Supernatural Grace, Gifts, and Virtues
Whew! They don't make this simple, do they?
Finally, baptism, once validly conferred, can never be repeated. The Fathers (St. Ambrose, Chrysostom, and others) so understand the words of St. Paul (Hebrews 6:4), and this has been the constant teaching of the Church both Eastern and Western from the earliest times. On this account, baptism is said to impress an ineffaceable character on the soul, which the Tridentine Fathers call a spiritual and indelible mark. That baptism (as well as Confirmation and Holy orders) really does imprint such a character, is defined explicitly by the Council of Trent (Sess. VII, can. ix). St. Cyril (Præp. in Cat.) calls baptism a "holy and indelible seal", and Clement of Alexandria (De Div. Serv., xlii), "the seal of the Lord". (5) Impression of a Character on the Soul.
So Protestants would agree here that baptism is a "sign and seal" of God's grace. However, the RC church goes so much further in the necessity for the administration of the sacrament and what it actually accomplishes...
...The early leaders of the so-called Reformation held very different doctrines from those of Christian antiquity on the effects of baptism. Luther (De Captiv. Bab.) and Calvin (Antid. C. Trid.) held that this sacrament made the baptized certain of the perpetual grace of adoption...The decrees of the Council of Trent, drawn up in opposition to the then prevailing errors, bear witness to the many strange and novel theories broached by various exponents of the nascent Protestant theology."
I found this statement interesting, in light of "strange and novel theories" which under-gird the apparent RC belief that baptism in and of itself confers salvation.
By the present authorized ritual of the Latin Church, baptism must be performed by a laving of the head of the candidate. Moralists, however, state that in case of necessity, the baptism would probably be valid if the water were applied to any other principal part of the body, as the breast or shoulder. In this case, however, conditional baptism would have to be administered if the person survived (St. Alph., no. 107). In like manner they consider as probably valid the baptism of an infant in its mother's womb, provided the water, by means of an instrument, would actually flow upon the child. Such baptism is, however, later to be repeated conditionally, if the child survives its birth (Lehmkuhl, n. 61). It is to be noted that it is not sufficient for the water to merely touch the candidate; it must also flow, otherwise there would seem to be no real ablution. At best, such a baptism would be considered doubtful. If the water touches only the hair, the sacrament has probably been validly conferred, though in practice the safer course must be followed. If only the clothes of the person have received the aspersion, the baptism is undoubtedly void...IV. Matter and Form of the Sacrament
Undoubtedly.
And they call us Calvinists "legalists." 8~)