可以在项目中通过使用静态链接库或手动引用libssl.dll来避免重复引用libssl.dll的问题。

1. 静态链接库：可以在vcpkg安装目录中找到libssl.a或libssl.lib文件，并在项目中添加该文件的路径和名称。

示例代码：

#include 
#include 
#include "openssl/ssl.h"
#pragma comment(lib, "libssl.lib")

int main() {
    SSL_library_init();
    SSL_CTX* ctx = SSL_CTX_new(SSLv23_client_method());
    SOCKET sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    SSL* ssl = SSL_new(ctx);
    SSL_set_fd(ssl, sock);
    int ret = SSL_connect(ssl);
    if (ret == 1) {
        printf("SSL connection is successful!\n");
    }
    SSL_free(ssl);
    SSL_CTX_free(ctx);
    closesocket(sock);
    return 0;
}

2. 手动引用libssl.dll：可以直接将libssl.dll复制到项目输出的可执行文件路径中，或者将libssl.dll的路径添加到系统环境变量中。

示例代码：

#include 
#include 
#include "openssl/ssl.h"

int main() {
    HINSTANCE hDLL = LoadLibrary("libssl.dll");
    if (hDLL == NULL) {
        printf("LoadLibrary failed!\n");
        return -1;
    }
    PF_SSL_library_init SSL_library_init = (PF_SSL_library_init)GetProcAddress(hDLL, "SSL_library_init");
    PF_SSL_CTX_new SSL_CTX_new = (PF_SSL_CTX_new)GetProcAddress(hDLL, "SSL_CTX_new");
    PF_socket socket = (PF_socket)GetProcAddress(hDLL, "socket");
    PF_SSL_new SSL_new = (PF_SSL_new)GetProcAddress(hDLL, "SSL_new");
    PF_SSL_set_fd SSL_set_fd = (PF_SSL_set_fd)GetProcAddress(hDLL, "SSL_set_fd");
    PF_SSL_connect SSL_connect = (PF_SSL_connect)GetProcAddress(hDLL, "SSL_connect");
    if (SSL_library_init