I presume when you say "2 records of marriage" you mean two entries in a marriage index; there is almost certainly only one record, and purchasing it (which can be done directly through the GRO; going through third parties only adds to the cost) would tell you exactly what the situation was.
The way that bmd records, including consular registrations, were indexed only allows for a single surname to be listed per 'entry'. So if a person is described as having/using more than one surname, there is no way to reflect than in the index except repeating the index entry multiple times, one for each name.
I'm also presuming the two entries have the same reference (volume/page) numbers, if they do not then something more out of the ordinary is going on.
Why is she listed twice, then?
It is unlikely in my opinion that it was because married before and widowed. Previous married names may be listed on the certificate, but widows are normally only indexed under their 'current' name at marriage.
In cases like this, there are two main potential reasons: one, that she was divorced, as divorcees usually appear under both married and maiden names on the index. Two, and probably the most likely in this case, that she was simply known by both names, Sborowitzova perhaps being her family's original name and Schonberg a Germanised variant, for example.