There are family trees on ancestry which say that Mary Ronan married John Bowland in 1882 at St. Alban's Roman Catholic church. He died then following year, the couple having had one child Lucy born , registered with the surname Boland. Mary Bowland then married James Carson in 1886 at Our Lady of Reconciliation Eidan St.
Both marriages are recorded in UKBMD as Liverpool, Register Office or Registrar Attended. If you know Mary Ronan was Roman Catholic, then this indicates that both John Bowland and James Carson were not.
If a non-Roman Catholic is to marry in a Roman Catholic church according to the full rites of the Roman Catholic church that person has to undertake instruction and become a member of the church. Should one party not wish to convert, a marriage ceremony can take place in the church but it is foreshortened from the full wedding mass. Normally, a clergyman/woman from the other denomination is also present; at least this is so in the last 30 years. My husband, who is Church of Scotand, married a Roman Catholic girl in her church. What a lot of folk haven't figured out is that no matter where a wedding takes place, the only actual legal part is the registration of the event. My guess is that if you look at the two certificates for Mary Ronan's marriages you find one of the following happened or something along those lines;
1. A registrar was present and conducted part of the ceremony.
2. The actual marriage was in a Register Office or some other place and what took place in the two churches were services of blessing.
Have you been to see the actual church registers for these events?