Spring boot WebClient sends multiple POST requests instead of one [closed]

I am using WebClient (Spring boot library) for sending client requests (POST) to the server. The WebClient sometimes unexpectedly sends multiple (upto 20) POST requests, even though I intended to send only one. As a result, a single record is stored multiple times on the server’s database, which is absurd.
Here is the code used for sending requests to the server:

   WebClient.builder()
            .baseUrl(baseUrl)
            .defaultHeader("Authorization","Bearer "+jwt)
            .codecs(codecs -> codecs
                    .defaultCodecs()
                    .maxInMemorySize(MB))
            .build().post().uri("/some/url/")
                .body(Mono.just(object),MyObject.class)
                .retrieve()
                .onStatus(HttpStatus::isError, clientResponse -> Mono.error(new      ClientRequestException ("ERROR:" + clientResponse.statusCode())))
                .bodyToMono(new ParameterizedTypeReference<ServiceResponse<ReturnedObject>>() {})
                .retryWhen(Retry.backoff(2, Duration.of(2, 
                   ChronoUnit.SECONDS))
                .onRetryExhaustedThrow((retryBackoffSpec, 
                   retrySignal) ->
                  new ClientRequestException("FAILED TO CONNECT")))
                .onErrorResume(ClientRequestException.class, ex -> 
                 { Platform.runLater(()-> 
                   ShowMessage.networkDown(table));
                   return Mono.empty();
                }).doOnSuccess(p->{ 
                   // show success message!!
                })
                .subscribe(); 

I tried to stop storing multiple same records in the database by setting the datetime column unique in the database’s table; however, this isn’t the right way to solve this problem.